diff --git a/src/Arguments.cc b/src/Arguments.cc
index a6e9f4b..15ddec2 100644
--- a/src/Arguments.cc
+++ b/src/Arguments.cc
@@ -2,6 +2,8 @@
 
 using namespace std;
 
+namespace phosg {
+
 Arguments::ArgText::ArgText(std::string&& text)
     : text(std::move(text)),
       used(false) {}
@@ -71,3 +73,5 @@ void Arguments::parse(vector<string>&& args) {
 }
 
 const string Arguments::empty_string;
+
+} // namespace phosg
diff --git a/src/Arguments.hh b/src/Arguments.hh
index 8eca9e7..8d27d7f 100644
--- a/src/Arguments.hh
+++ b/src/Arguments.hh
@@ -7,7 +7,7 @@
 
 #include "Strings.hh"
 
-using namespace std;
+namespace phosg {
 
 class Arguments {
 public:
@@ -24,7 +24,7 @@ public:
 
   template <typename RetT>
     requires(std::is_same_v<RetT, std::string>)
-  std::vector<RetT> get_multi(const string& name) {
+  std::vector<RetT> get_multi(const std::string& name) {
     std::vector<std::string> ret;
     for (auto& value : this->get_values_multi(name)) {
       ret.emplace_back(value.text);
@@ -34,7 +34,7 @@ public:
   }
   template <typename RetT>
     requires(std::is_same_v<RetT, std::string>)
-  const RetT& get(const string& name, bool throw_if_missing = false) {
+  const RetT& get(const std::string& name, bool throw_if_missing = false) {
     try {
       auto& values = this->named.at(name);
       if (values.empty()) {
@@ -47,7 +47,7 @@ public:
       }
       values[0].used = true;
       return values[0].text;
-    } catch (const out_of_range&) {
+    } catch (const std::out_of_range&) {
       if (throw_if_missing) {
         throw std::out_of_range(Arguments::exc_prefix(name) + "argument is missing");
       } else {
@@ -62,7 +62,7 @@ public:
       auto& arg = this->positional.at(position);
       arg.used = true;
       return arg.text;
-    } catch (const out_of_range&) {
+    } catch (const std::out_of_range&) {
       if (throw_if_missing) {
         throw std::out_of_range(Arguments::exc_prefix(position) + "argument is missing");
       } else {
@@ -155,17 +155,17 @@ private:
 
   void parse(std::vector<std::string>&& args);
 
-  inline std::vector<ArgText>& get_values_multi(const string& name) {
+  inline std::vector<ArgText>& get_values_multi(const std::string& name) {
     try {
       return this->named.at(name);
-    } catch (const out_of_range&) {
+    } catch (const std::out_of_range&) {
       static std::vector<ArgText> empty_vec;
       return empty_vec;
     }
   }
 
   static inline std::string exc_prefix(const std::string& name) {
-    string ret = "(";
+    std::string ret = "(";
     ret += name;
     ret += ") ";
     return ret;
@@ -241,3 +241,5 @@ private:
 };
 
 std::vector<std::string> split_args(const std::string& s);
+
+} // namespace phosg
diff --git a/src/ArgumentsTest.cc b/src/ArgumentsTest.cc
index 51a593a..6207fc1 100644
--- a/src/ArgumentsTest.cc
+++ b/src/ArgumentsTest.cc
@@ -5,6 +5,9 @@
 #include "Encoding.hh"
 #include "UnitTest.hh"
 
+using namespace std;
+using namespace phosg;
+
 int main(int, char**) {
   Arguments a("pos0 --named1 300 --named2=value2 4.0 --int3=40000 --float4=2.0");
 
diff --git a/src/BinDiff.cc b/src/BinDiff.cc
index c3e7c31..efdf6cd 100644
--- a/src/BinDiff.cc
+++ b/src/BinDiff.cc
@@ -8,6 +8,7 @@
 #include "JSON.hh"
 
 using namespace std;
+using namespace phosg;
 
 void print_usage() {
   fprintf(stderr, "\
diff --git a/src/Containers.hh b/src/Containers.hh
index d39a0b5..76b4f7c 100644
--- a/src/Containers.hh
+++ b/src/Containers.hh
@@ -6,6 +6,8 @@
 #include <unordered_set>
 #include <vector>
 
+namespace phosg {
+
 template <typename V>
 std::vector<V> set_to_vec(const std::set<V>& s) {
   std::vector<V> ret;
@@ -83,3 +85,5 @@ std::vector<K> map_values_to_vec(const std::unordered_map<K, V>& s) {
   }
   return ret;
 }
+
+} // namespace phosg
diff --git a/src/Encoding.cc b/src/Encoding.cc
index dfca723..59b054c 100644
--- a/src/Encoding.cc
+++ b/src/Encoding.cc
@@ -4,6 +4,8 @@
 
 using namespace std;
 
+namespace phosg {
+
 const char* DEFAULT_ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 const char* URLSAFE_ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
 
@@ -131,3 +133,5 @@ string rot13(const void* vdata, size_t size) {
   }
   return ret;
 }
+
+} // namespace phosg
diff --git a/src/Encoding.hh b/src/Encoding.hh
index 799cf1e..a21a31e 100644
--- a/src/Encoding.hh
+++ b/src/Encoding.hh
@@ -8,6 +8,8 @@
 #include "Platform.hh"
 #include "Types.hh"
 
+namespace phosg {
+
 template <typename T>
 constexpr uint8_t bits_for_type = sizeof(T) << 3;
 
@@ -465,3 +467,5 @@ std::string base64_decode(const void* data, size_t size, const char* alphabet =
 std::string base64_decode(const std::string& data, const char* alphabet = nullptr);
 
 std::string rot13(const void* data, size_t size);
+
+} // namespace phosg
diff --git a/src/EncodingTest.cc b/src/EncodingTest.cc
index ca6264a..eaf3646 100644
--- a/src/EncodingTest.cc
+++ b/src/EncodingTest.cc
@@ -4,6 +4,8 @@
 #include "Encoding.hh"
 #include "UnitTest.hh"
 
+using namespace phosg;
+
 int main(int, char**) {
   expect_eq(0x0000, (sign_extend<uint16_t, uint8_t>(0x00)));
   expect_eq(0x0001, (sign_extend<uint16_t, uint8_t>(0x01)));
diff --git a/src/Filesystem.cc b/src/Filesystem.cc
index 82094bc..2a34366 100644
--- a/src/Filesystem.cc
+++ b/src/Filesystem.cc
@@ -27,6 +27,8 @@
 
 using namespace std;
 
+namespace phosg {
+
 std::string basename(const std::string& filename) {
   size_t slash_pos = filename.rfind('/');
   return (slash_pos == string::npos) ? filename : filename.substr(slash_pos + 1);
@@ -82,7 +84,7 @@ vector<string> list_directory_sorted(const string& dirname) {
 
 string getcwd() {
   string ret(MAXPATHLEN, '\0');
-  if (!getcwd(ret.data(), ret.size())) {
+  if (!::getcwd(ret.data(), ret.size())) {
     throw runtime_error("cannot get working directory");
   }
   ret.resize(strlen(ret.c_str()));
@@ -140,7 +142,7 @@ io_error::io_error(int fd, const string& what)
 
 struct stat stat(const string& filename) {
   struct stat st;
-  if (stat(filename.c_str(), &st)) {
+  if (::stat(filename.c_str(), &st)) {
     throw cannot_stat_file(filename);
   }
   return st;
@@ -148,7 +150,7 @@ struct stat stat(const string& filename) {
 
 struct stat lstat(const string& filename) {
   struct stat st;
-  if (lstat(filename.c_str(), &st)) {
+  if (::lstat(filename.c_str(), &st)) {
     throw cannot_stat_file(filename);
   }
   return st;
@@ -156,7 +158,7 @@ struct stat lstat(const string& filename) {
 
 struct stat fstat(int fd) {
   struct stat st;
-  if (fstat(fd, &st)) {
+  if (::fstat(fd, &st)) {
     throw cannot_stat_file(fd);
   }
   return st;
@@ -220,7 +222,7 @@ bool islink(const string& filename) {
 
 string readlink(const string& filename) {
   string data(1024, 0);
-  ssize_t length = readlink(filename.c_str(), data.data(), data.size());
+  ssize_t length = ::readlink(filename.c_str(), data.data(), data.size());
   if (length < 0) {
     throw cannot_stat_file(filename);
   }
@@ -231,7 +233,7 @@ string readlink(const string& filename) {
 
 string realpath(const string& path) {
   string data(PATH_MAX, 0);
-  if (!realpath(path.c_str(), data.data())) {
+  if (!::realpath(path.c_str(), data.data())) {
     throw cannot_stat_file(path);
   }
   data.resize(strlen(data.c_str()));
@@ -307,7 +309,7 @@ string read_all(int fd) {
   vector<string> buffers;
   for (;;) {
     buffers.emplace_back(read_size, 0);
-    ssize_t bytes_read = read(fd, buffers.back().data(), read_size);
+    ssize_t bytes_read = ::read(fd, buffers.back().data(), read_size);
     if (bytes_read < 0) {
       throw io_error(fd);
     }
@@ -339,7 +341,7 @@ string read_all(FILE* f) {
   vector<string> buffers;
   for (;;) {
     buffers.emplace_back(read_size, 0);
-    ssize_t bytes_read = fread(buffers.back().data(), 1, read_size, f);
+    ssize_t bytes_read = ::fread(buffers.back().data(), 1, read_size, f);
     if (bytes_read < 0) {
       throw io_error(fileno(f));
     }
@@ -366,7 +368,7 @@ string read_all(FILE* f) {
 
 string read(int fd, size_t size) {
   string data(size, '\0');
-  ssize_t ret_size = read(fd, data.data(), size);
+  ssize_t ret_size = ::read(fd, data.data(), size);
   if (ret_size < 0) {
     throw io_error(fd);
   } else if (ret_size != static_cast<ssize_t>(size)) {
@@ -377,7 +379,7 @@ string read(int fd, size_t size) {
 
 string fread(FILE* f, size_t size) {
   string data(size, '\0');
-  ssize_t ret_size = fread(data.data(), 1, size, f);
+  ssize_t ret_size = ::fread(data.data(), 1, size, f);
   if (ret_size < 0) {
     throw io_error(fileno(f));
   } else if (ret_size != static_cast<ssize_t>(size)) {
@@ -387,7 +389,7 @@ string fread(FILE* f, size_t size) {
 }
 
 void readx(int fd, void* data, size_t size) {
-  ssize_t ret_size = read(fd, data, size);
+  ssize_t ret_size = ::read(fd, data, size);
   if (ret_size < 0) {
     throw io_error(fd);
   } else if (ret_size != static_cast<ssize_t>(size)) {
@@ -415,7 +417,7 @@ void writex(int fd, const string& data) {
 }
 
 void preadx(int fd, void* data, size_t size, off_t offset) {
-  ssize_t ret_size = pread(fd, data, size, offset);
+  ssize_t ret_size = ::pread(fd, data, size, offset);
   if (ret_size < 0) {
     throw io_error(fd);
   } else if (ret_size != static_cast<ssize_t>(size)) {
@@ -424,7 +426,7 @@ void preadx(int fd, void* data, size_t size, off_t offset) {
 }
 
 void pwritex(int fd, const void* data, size_t size, off_t offset) {
-  ssize_t ret_size = pwrite(fd, data, size, offset);
+  ssize_t ret_size = ::pwrite(fd, data, size, offset);
   if (ret_size < 0) {
     throw io_error(fd);
   } else if (ret_size != static_cast<ssize_t>(size)) {
@@ -443,7 +445,7 @@ void pwritex(int fd, const string& data, off_t offset) {
 }
 
 void freadx(FILE* f, void* data, size_t size) {
-  ssize_t ret_size = fread(data, 1, size, f);
+  ssize_t ret_size = ::fread(data, 1, size, f);
   if (ret_size < 0) {
     throw io_error(fileno(f));
   } else if (ret_size != static_cast<ssize_t>(size)) {
@@ -452,7 +454,7 @@ void freadx(FILE* f, void* data, size_t size) {
 }
 
 void fwritex(FILE* f, const void* data, size_t size) {
-  ssize_t ret_size = fwrite(data, 1, size, f);
+  ssize_t ret_size = ::fwrite(data, 1, size, f);
   if (ret_size < 0) {
     throw io_error(fileno(f));
   } else if (ret_size != static_cast<ssize_t>(size)) {
@@ -471,7 +473,7 @@ void fwritex(FILE* f, const string& data) {
 }
 
 uint8_t fgetcx(FILE* f) {
-  int ret = fgetc(f);
+  int ret = ::fgetc(f);
   if (ret == EOF) {
     if (feof(f)) {
       throw io_error(fileno(f), "end of stream");
@@ -486,9 +488,9 @@ std::string fgets(FILE* f) {
   deque<std::string> blocks;
   for (;;) {
     std::string& block = blocks.emplace_back(0x100, '\0');
-    if (!fgets(block.data(), block.size(), f)) {
+    if (!::fgets(block.data(), block.size(), f)) {
       blocks.pop_back();
-      if (feof(f)) {
+      if (::feof(f)) {
         break;
       } else {
         throw io_error(fileno(f), "cannot read from stream");
@@ -513,7 +515,7 @@ string load_file(const string& filename) {
   ssize_t file_size = fstat(fd).st_size;
 
   string data(file_size, 0);
-  ssize_t bytes_read = read(fd, data.data(), data.size());
+  ssize_t bytes_read = ::read(fd, data.data(), data.size());
   if (bytes_read != file_size) {
     if (errno == 0) {
       throw runtime_error(string_printf("can\'t read from %s: %zd/%zd bytes read",
@@ -571,11 +573,9 @@ static void fclose_raw(FILE* f) {
   fclose(f);
 }
 
-unique_ptr<FILE, void (*)(FILE*)> fopen_unique(const string& filename,
-    const string& mode, FILE* dash_file) {
+unique_ptr<FILE, void (*)(FILE*)> fopen_unique(const string& filename, const string& mode, FILE* dash_file) {
   if (dash_file && (filename == "-")) {
-    return unique_ptr<FILE, void (*)(FILE*)>(
-        dash_file, +[](FILE*) {});
+    return unique_ptr<FILE, void (*)(FILE*)>(dash_file, +[](FILE*) {});
   }
   return unique_ptr<FILE, void (*)(FILE*)>(fopen_binary_raw(filename, mode), fclose_raw);
 }
@@ -585,13 +585,10 @@ unique_ptr<FILE, void (*)(FILE*)> fdopen_unique(int fd, const string& mode) {
 }
 
 unique_ptr<FILE, void (*)(FILE*)> fmemopen_unique(const void* buf, size_t size) {
-  return unique_ptr<FILE, void (*)(FILE*)>(fmemopen(
-                                               const_cast<void*>(buf), size, "rb"),
-      fclose_raw);
+  return unique_ptr<FILE, void (*)(FILE*)>(fmemopen(const_cast<void*>(buf), size, "rb"), fclose_raw);
 }
 
-shared_ptr<FILE> fopen_shared(const string& filename, const string& mode,
-    FILE* dash_file) {
+shared_ptr<FILE> fopen_shared(const string& filename, const string& mode, FILE* dash_file) {
   if (dash_file && (filename == "-")) {
     return shared_ptr<FILE>(dash_file, [](FILE*) {});
   }
@@ -603,7 +600,7 @@ shared_ptr<FILE> fdopen_shared(int fd, const string& mode) {
 }
 
 void rename(const std::string& old_filename, const std::string& new_filename) {
-  if (rename(old_filename.c_str(), new_filename.c_str()) != 0) {
+  if (::rename(old_filename.c_str(), new_filename.c_str()) != 0) {
     throw runtime_error("can\'t rename file " + old_filename + " to " + new_filename + ": " + string_for_error(errno));
   }
 }
@@ -614,7 +611,7 @@ void unlink(const string& filename, bool recursive) {
       for (const string& item : list_directory(filename)) {
         unlink(filename + "/" + item, true);
       }
-      if ((rmdir(filename.c_str()) != 0) && (errno != ENOENT)) {
+      if ((::rmdir(filename.c_str()) != 0) && (errno != ENOENT)) {
         throw runtime_error("can\'t delete directory " + filename + ": " + string_for_error(errno));
       }
     } else {
@@ -622,7 +619,7 @@ void unlink(const string& filename, bool recursive) {
     }
 
   } else {
-    if ((unlink(filename.c_str()) != 0) && (errno != ENOENT)) {
+    if ((::unlink(filename.c_str()) != 0) && (errno != ENOENT)) {
       throw runtime_error("can\'t delete file " + filename + ": " + string_for_error(errno));
     }
   }
@@ -640,7 +637,7 @@ void make_fd_nonblocking(int fd) {
 
 pair<int, int> pipe() {
   int fds[2];
-  if (pipe(fds)) {
+  if (::pipe(fds)) {
     throw runtime_error("pipe failed: " + string_for_error(errno));
   }
   return make_pair(fds[0], fds[1]);
@@ -700,3 +697,5 @@ unordered_map<int, short> Poll::poll(int timeout_ms) {
   }
   return ret;
 }
+
+} // namespace phosg
diff --git a/src/Filesystem.hh b/src/Filesystem.hh
index 1e907d8..41fbc9b 100644
--- a/src/Filesystem.hh
+++ b/src/Filesystem.hh
@@ -20,6 +20,8 @@
 #include <utility>
 #include <vector>
 
+namespace phosg {
+
 std::string basename(const std::string& filename);
 std::string dirname(const std::string& filename);
 
@@ -98,15 +100,6 @@ private:
   int fd;
 };
 
-namespace std {
-template <>
-struct hash<scoped_fd> {
-  size_t operator()(const scoped_fd& fd) const {
-    return std::hash<int>()(static_cast<int>(fd));
-  }
-};
-} // namespace std
-
 std::string read_all(int fd);
 std::string read_all(FILE* f);
 
@@ -167,6 +160,10 @@ void fwritex(FILE* f, const T& t) {
   fwritex(f, &t, sizeof(T));
 }
 
+std::string load_file(const std::string& filename);
+void save_file(const std::string& filename, const void* data, size_t size);
+void save_file(const std::string& filename, const std::string& data);
+
 template <typename T>
 T load_object_file(const std::string& filename, bool allow_oversize = false) {
   scoped_fd fd(filename, O_RDONLY);
@@ -203,10 +200,6 @@ void save_vector_file(const std::string& filename, const std::vector<T>& v) {
   save_file(filename, v.data(), v.size() * sizeof(T));
 }
 
-std::string load_file(const std::string& filename);
-void save_file(const std::string& filename, const void* data, size_t size);
-void save_file(const std::string& filename, const std::string& data);
-
 std::unique_ptr<FILE, void (*)(FILE*)> fopen_unique(const std::string& filename,
     const std::string& mode = "rb", FILE* dash_file = nullptr);
 std::unique_ptr<FILE, void (*)(FILE*)> fdopen_unique(int fd,
@@ -238,3 +231,5 @@ public:
 private:
   std::vector<struct pollfd> poll_fds;
 };
+
+} // namespace phosg
diff --git a/src/FilesystemTest.cc b/src/FilesystemTest.cc
index 43b4b0f..f22bc51 100644
--- a/src/FilesystemTest.cc
+++ b/src/FilesystemTest.cc
@@ -6,6 +6,7 @@
 #include "UnitTest.hh"
 
 using namespace std;
+using namespace phosg;
 
 int main(int, char**) {
   {
diff --git a/src/Hash.cc b/src/Hash.cc
index 1c634cf..b2deff5 100644
--- a/src/Hash.cc
+++ b/src/Hash.cc
@@ -11,6 +11,8 @@
 
 using namespace std;
 
+namespace phosg {
+
 uint32_t fnv1a32(const void* data, size_t size, uint32_t hash) {
   const uint8_t* data_ptr = reinterpret_cast<const uint8_t*>(data);
   const uint8_t* end_ptr = data_ptr + size;
@@ -366,3 +368,5 @@ uint32_t crc32(const void* vdata, size_t size, uint32_t cs) {
   }
   return ~cs;
 }
+
+} // namespace phosg
diff --git a/src/Hash.hh b/src/Hash.hh
index bb7d857..0a9be52 100644
--- a/src/Hash.hh
+++ b/src/Hash.hh
@@ -4,15 +4,17 @@
 
 #include <stdint.h>
 
-#define fnv1a32_start 0x811C9DC5
+namespace phosg {
 
-uint32_t fnv1a32(const void* data, size_t size, uint32_t hash = fnv1a32_start);
-uint32_t fnv1a32(const std::string& data, uint32_t hash = fnv1a32_start);
+constexpr uint32_t FNV1A32_START = 0x811C9DC5;
 
-#define fnv1a64_start 0xCBF29CE484222325
+uint32_t fnv1a32(const void* data, size_t size, uint32_t hash = FNV1A32_START);
+uint32_t fnv1a32(const std::string& data, uint32_t hash = FNV1A32_START);
 
-uint64_t fnv1a64(const void* data, size_t size, uint64_t hash = fnv1a64_start);
-uint64_t fnv1a64(const std::string& data, uint64_t hash = fnv1a64_start);
+constexpr uint64_t FNV1A64_START = 0xCBF29CE484222325;
+
+uint64_t fnv1a64(const void* data, size_t size, uint64_t hash = FNV1A64_START);
+uint64_t fnv1a64(const std::string& data, uint64_t hash = FNV1A64_START);
 
 std::string sha1(const void* data, size_t size);
 std::string sha1(const std::string& data);
@@ -24,3 +26,5 @@ std::string md5(const void* data, size_t size);
 std::string md5(const std::string& data);
 
 uint32_t crc32(const void* vdata, size_t size, uint32_t cs = 0);
+
+} // namespace phosg
diff --git a/src/HashTest.cc b/src/HashTest.cc
index 053eb7b..6aa9778 100644
--- a/src/HashTest.cc
+++ b/src/HashTest.cc
@@ -6,6 +6,7 @@
 #include "UnitTest.hh"
 
 using namespace std;
+using namespace phosg;
 
 int main(int, char**) {
   {
diff --git a/src/Image.cc b/src/Image.cc
index ceea66b..13b8cf5 100644
--- a/src/Image.cc
+++ b/src/Image.cc
@@ -23,6 +23,8 @@
 
 using namespace std;
 
+namespace phosg {
+
 Image::unknown_format::unknown_format(const std::string& what) : runtime_error(what) {}
 
 struct ExpandedColor {
@@ -1715,3 +1717,5 @@ void Image::resize_blit(const Image& source, ssize_t x, ssize_t y, ssize_t w,
     }
   }
 }
+
+} // namespace phosg
diff --git a/src/Image.hh b/src/Image.hh
index 8089755..c56f17b 100644
--- a/src/Image.hh
+++ b/src/Image.hh
@@ -9,6 +9,8 @@
 
 #include "Platform.hh"
 
+namespace phosg {
+
 // an Image represents a drawing canvas. this class is fairly simple; it
 // supports reading/writing individual pixels, drawing lines, and saving the
 // image as a PPM or Windows BMP file.
@@ -193,3 +195,5 @@ private:
   template <typename Writer>
   void save_helper(Format format, Writer&& writer) const;
 };
+
+} // namespace phosg
diff --git a/src/ImageTest.cc b/src/ImageTest.cc
index 5b8988f..225aa9e 100644
--- a/src/ImageTest.cc
+++ b/src/ImageTest.cc
@@ -11,6 +11,7 @@
 #include "UnitTest.hh"
 
 using namespace std;
+using namespace phosg;
 
 struct Color {
   uint8_t r;
diff --git a/src/ImageTextFont.hh b/src/ImageTextFont.hh
index 487bf1f..43663a1 100644
--- a/src/ImageTextFont.hh
+++ b/src/ImageTextFont.hh
@@ -1,5 +1,7 @@
 #pragma once
 
+namespace phosg {
+
 // clang-format off
 static uint8_t font[96][35] = {
   { 0,0,0,0,0,
@@ -676,3 +678,5 @@ static uint8_t font[96][35] = {
     1,1,1,1,1}, //0x7F
 };
 // clang-format on
+
+} // namespace phosg
diff --git a/src/JSON.cc b/src/JSON.cc
index a37d4ce..41769b2 100644
--- a/src/JSON.cc
+++ b/src/JSON.cc
@@ -11,6 +11,8 @@
 
 using namespace std;
 
+namespace phosg {
+
 JSON::parse_error::parse_error(const string& what) : runtime_error(what) {}
 JSON::type_error::type_error(const string& what) : runtime_error(what) {}
 
@@ -744,3 +746,5 @@ void JSON::clear() {
       throw type_error("cannot clear primitive JSON value");
   }
 }
+
+} // namespace phosg
diff --git a/src/JSON.hh b/src/JSON.hh
index 8ecaf27..2fdaf3d 100644
--- a/src/JSON.hh
+++ b/src/JSON.hh
@@ -12,6 +12,8 @@
 #include "Strings.hh"
 #include "Types.hh"
 
+namespace phosg {
+
 class JSON {
 public:
   enum class StringEscapeMode {
@@ -477,3 +479,5 @@ private:
       dict_type>
       value;
 };
+
+} // namespace phosg
diff --git a/src/JSONFormat.cc b/src/JSONFormat.cc
index 24378ed..cf470e6 100644
--- a/src/JSONFormat.cc
+++ b/src/JSONFormat.cc
@@ -8,6 +8,7 @@
 #include "JSON.hh"
 
 using namespace std;
+using namespace phosg;
 
 void print_usage() {
   fprintf(stderr, "\
diff --git a/src/JSONTest.cc b/src/JSONTest.cc
index d859441..aef21e3 100644
--- a/src/JSONTest.cc
+++ b/src/JSONTest.cc
@@ -9,6 +9,7 @@
 #include "UnitTest.hh"
 
 using namespace std;
+using namespace phosg;
 
 enum JSONTestEnum {
   ONE = 1,
@@ -17,7 +18,7 @@ enum JSONTestEnum {
 };
 
 template <>
-JSONTestEnum enum_for_name<JSONTestEnum>(const char* name) {
+JSONTestEnum phosg::enum_for_name<JSONTestEnum>(const char* name) {
   if (!strcmp(name, "ONE")) {
     return JSONTestEnum::ONE;
   } else if (!strcmp(name, "TWO")) {
@@ -30,7 +31,7 @@ JSONTestEnum enum_for_name<JSONTestEnum>(const char* name) {
 }
 
 template <>
-const char* name_for_enum<JSONTestEnum>(JSONTestEnum v) {
+const char* phosg::name_for_enum<JSONTestEnum>(JSONTestEnum v) {
   switch (v) {
     case JSONTestEnum::ONE:
       return "ONE";
diff --git a/src/KDTree-inl.hh b/src/KDTree-inl.hh
index d2b5661..608b4f8 100644
--- a/src/KDTree-inl.hh
+++ b/src/KDTree-inl.hh
@@ -9,6 +9,8 @@
 #include <utility>
 #include <vector>
 
+namespace phosg {
+
 template <typename CoordType, typename ValueType>
 KDTree<CoordType, ValueType>::KDTree()
     : root(nullptr),
@@ -530,3 +532,5 @@ typename KDTree<CoordType, ValueType>::Iterator
 KDTree<CoordType, ValueType>::end() const {
   return Iterator(nullptr);
 }
+
+} // namespace phosg
diff --git a/src/KDTree.hh b/src/KDTree.hh
index 013c878..8a7ea58 100644
--- a/src/KDTree.hh
+++ b/src/KDTree.hh
@@ -7,6 +7,8 @@
 #include <memory>
 #include <vector>
 
+namespace phosg {
+
 template <typename CoordType, typename ValueType>
 class KDTree {
 private:
@@ -94,4 +96,6 @@ public:
   Iterator end() const;
 };
 
+} // namespace phosg
+
 #include "KDTree-inl.hh"
diff --git a/src/KDTreeTest.cc b/src/KDTreeTest.cc
index e52eec1..e167384 100644
--- a/src/KDTreeTest.cc
+++ b/src/KDTreeTest.cc
@@ -11,6 +11,7 @@
 #include "Vector.hh"
 
 using namespace std;
+using namespace phosg;
 
 void run_randomized_test() {
   printf("-- randomized\n");
diff --git a/src/LRUMap.hh b/src/LRUMap.hh
index 01c051e..ed6ed4d 100644
--- a/src/LRUMap.hh
+++ b/src/LRUMap.hh
@@ -6,6 +6,8 @@
 #include <stdexcept>
 #include <unordered_map>
 
+namespace phosg {
+
 template <typename KeyT, typename ValueT>
 class LRUMap {
 protected:
@@ -264,3 +266,5 @@ public:
     other.total_size = this_total_size;
   }
 };
+
+} // namespace phosg
diff --git a/src/LRUMapTest.cc b/src/LRUMapTest.cc
index d1ca413..f7cfafb 100644
--- a/src/LRUMapTest.cc
+++ b/src/LRUMapTest.cc
@@ -6,6 +6,7 @@
 #include "UnitTest.hh"
 
 using namespace std;
+using namespace phosg;
 
 int main(int, char**) {
   LRUMap<string, string> c;
diff --git a/src/LRUSet-inl.hh b/src/LRUSet-inl.hh
index a9cfeb4..4a0dca0 100644
--- a/src/LRUSet-inl.hh
+++ b/src/LRUSet-inl.hh
@@ -4,6 +4,8 @@
 #include <unordered_map>
 #include <utility>
 
+namespace phosg {
+
 template <typename K>
 LRUSet<K>::Item::Item(size_t size)
     : prev(nullptr),
@@ -195,3 +197,5 @@ void LRUSet<K>::swap(LRUSet<K>& other) {
   other.tail = this_tail;
   other.total_size = this_total_size;
 }
+
+} // namespace phosg
diff --git a/src/LRUSet.hh b/src/LRUSet.hh
index b7e6a29..ad6ad6e 100644
--- a/src/LRUSet.hh
+++ b/src/LRUSet.hh
@@ -5,6 +5,8 @@
 
 #include <unordered_map>
 
+namespace phosg {
+
 template <typename K>
 class LRUSet {
 protected:
@@ -50,4 +52,6 @@ public:
   void swap(LRUSet<K>& other);
 };
 
+} // namespace phosg
+
 #include "LRUSet-inl.hh"
diff --git a/src/LRUSetTest.cc b/src/LRUSetTest.cc
index 8e952b3..a0bf22c 100644
--- a/src/LRUSetTest.cc
+++ b/src/LRUSetTest.cc
@@ -6,6 +6,7 @@
 #include "UnitTest.hh"
 
 using namespace std;
+using namespace phosg;
 
 int main(int, char**) {
   LRUSet<string> c;
diff --git a/src/Math.hh b/src/Math.hh
index 416e113..b7e4426 100644
--- a/src/Math.hh
+++ b/src/Math.hh
@@ -1,5 +1,7 @@
 #include <utility>
 
+namespace phosg {
+
 template <typename IntT>
 constexpr IntT gcd(IntT a, IntT b) {
   if (b == 0) {
@@ -18,3 +20,5 @@ template <typename IntT>
 constexpr IntT log2i(IntT v) {
   return (sizeof(IntT) << 3) - 1 - __builtin_clz(v);
 }
+
+} // namespace phosg
diff --git a/src/Network.cc b/src/Network.cc
index e5df876..c4f399b 100644
--- a/src/Network.cc
+++ b/src/Network.cc
@@ -26,6 +26,8 @@
 
 using namespace std;
 
+namespace phosg {
+
 uint32_t resolve_ipv4(const string& addr) {
   struct addrinfo* res0;
   if (getaddrinfo(addr.c_str(), nullptr, nullptr, &res0)) {
@@ -184,7 +186,7 @@ int listen(const string& addr, int port, int backlog, bool nonblocking) {
   }
 
   // Only listen() on stream sockets
-  if (backlog && (listen(fd, backlog) != 0)) {
+  if (backlog && (::listen(fd, backlog) != 0)) {
     close(fd);
     throw runtime_error("can\'t listen on socket: " + string_for_error(errno));
   }
@@ -257,7 +259,7 @@ pair<string, uint16_t> parse_netloc(const string& netloc, int default_port) {
 
 string gethostname() {
   string buf(sysconf(_SC_HOST_NAME_MAX) + 1, '\0');
-  if (gethostname(buf.data(), buf.size())) {
+  if (::gethostname(buf.data(), buf.size())) {
     throw runtime_error("can\'t get hostname");
   }
   buf.resize(strlen(buf.c_str()));
@@ -266,7 +268,7 @@ string gethostname() {
 
 pair<int, int> socketpair(int domain, int type, int protocol) {
   int fds[2];
-  if (socketpair(domain, type, protocol, fds)) {
+  if (::socketpair(domain, type, protocol, fds)) {
     throw runtime_error("socketpair failed: " + string_for_error(errno));
   }
   return make_pair(fds[0], fds[1]);
@@ -289,3 +291,5 @@ unordered_map<string, struct sockaddr_storage> get_network_interfaces() {
 
   return ret;
 }
+
+} // namespace phosg
diff --git a/src/Network.hh b/src/Network.hh
index f125dcb..00a19d1 100644
--- a/src/Network.hh
+++ b/src/Network.hh
@@ -8,6 +8,8 @@
 #include <unordered_map>
 #include <utility>
 
+namespace phosg {
+
 std::pair<struct sockaddr_storage, size_t> make_sockaddr_storage(
     const std::string& addr, uint16_t port);
 
@@ -66,3 +68,5 @@ std::pair<int, int> socketpair(
     int protocol = 0);
 
 std::unordered_map<std::string, struct sockaddr_storage> get_network_interfaces();
+
+} // namespace phosg
diff --git a/src/ParseData.cc b/src/ParseData.cc
index 6e632f1..658db2e 100644
--- a/src/ParseData.cc
+++ b/src/ParseData.cc
@@ -8,6 +8,7 @@
 #include "Strings.hh"
 
 using namespace std;
+using namespace phosg;
 
 int main(int argc, char** argv) {
   const char* src_filename = (argc > 1) ? argv[1] : nullptr;
diff --git a/src/PhosgPNGConv.cc b/src/PhosgPNGConv.cc
index 006bbe8..1368c69 100644
--- a/src/PhosgPNGConv.cc
+++ b/src/PhosgPNGConv.cc
@@ -9,6 +9,7 @@
 #include "Strings.hh"
 
 using namespace std;
+using namespace phosg;
 
 int main(int argc, char** argv) {
   const char* src_filename = (argc > 1) ? argv[1] : nullptr;
diff --git a/src/Platform.hh b/src/Platform.hh
index b05ee19..51047d6 100644
--- a/src/Platform.hh
+++ b/src/Platform.hh
@@ -2,6 +2,8 @@
 
 #include <stdint.h>
 
+namespace phosg {
+
 #if defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(__NT__) || defined(__CYGWIN__)
 #define PHOSG_WINDOWS
 
@@ -58,3 +60,5 @@
 
 // Define some useful shortcuts
 #define ATTR_PRINTF(x, y) __attribute__((format(printf, x, y)))
+
+} // namespace phosg
diff --git a/src/Process.cc b/src/Process.cc
index 502ca76..6a1c444 100644
--- a/src/Process.cc
+++ b/src/Process.cc
@@ -28,6 +28,8 @@
 
 using namespace std;
 
+namespace phosg {
+
 unique_ptr<FILE, void (*)(FILE*)> popen_unique(const string& command,
     const string& mode) {
   unique_ptr<FILE, void (*)(FILE*)> f(
@@ -508,8 +510,7 @@ SubprocessResult run_process(const vector<string>& cmd, const string* stdin_data
   struct Buffer {
     const string* buf;
     size_t offset;
-    Buffer(const string* buf) : buf(buf),
-                                offset(0) {}
+    Buffer(const string* buf) : buf(buf), offset(0) {}
   };
   unordered_map<int, Buffer> write_fd_to_buffer;
   unordered_map<int, string*> read_fd_to_buffer;
@@ -526,15 +527,14 @@ SubprocessResult run_process(const vector<string>& cmd, const string* stdin_data
   read_fd_to_buffer.emplace(sp.stderr_fd(), &ret.stderr_contents);
   p.add(sp.stderr_fd(), POLLIN);
 
-  // read/write to pipes as long as the process is running
+  // Read and write to pipes as long as the process is running
   while ((ret.exit_status = sp.wait(true)) == -1) {
     for (const auto& pfd : p.poll(1000)) {
       if (pfd.second & POLLIN) {
         string* buf = read_fd_to_buffer.at(pfd.first);
         size_t read_offset = buf->size();
         buf->resize(read_offset + READ_BLOCK_SIZE);
-        ssize_t bytes_read = read(pfd.first, buf->data() + read_offset,
-            READ_BLOCK_SIZE);
+        ssize_t bytes_read = ::read(pfd.first, buf->data() + read_offset, READ_BLOCK_SIZE);
         if (bytes_read > 0) {
           buf->resize(read_offset + bytes_read);
         } else if (bytes_read < 0) {
@@ -585,13 +585,12 @@ SubprocessResult run_process(const vector<string>& cmd, const string* stdin_data
   }
   ret.elapsed_time = now() - ret.elapsed_time;
 
-  // read any leftover data after termination
+  // Read any leftover data after termination
   for (auto& it : read_fd_to_buffer) {
     for (;;) {
       size_t read_offset = it.second->size();
       it.second->resize(read_offset + READ_BLOCK_SIZE);
-      ssize_t bytes_read = read(it.first, it.second->data() + read_offset,
-          READ_BLOCK_SIZE);
+      ssize_t bytes_read = ::read(it.first, it.second->data() + read_offset, READ_BLOCK_SIZE);
       if (bytes_read > 0) {
         it.second->resize(it.second->size() - READ_BLOCK_SIZE + bytes_read);
       } else if (bytes_read < 0) {
@@ -614,3 +613,5 @@ SubprocessResult run_process(const vector<string>& cmd, const string* stdin_data
 
   return ret;
 }
+
+} // namespace phosg
diff --git a/src/Process.hh b/src/Process.hh
index 240de2e..0eb1d32 100644
--- a/src/Process.hh
+++ b/src/Process.hh
@@ -11,8 +11,9 @@
 #include <unordered_set>
 #include <vector>
 
-std::unique_ptr<FILE, void (*)(FILE*)> popen_unique(const std::string& command,
-    const std::string& mode);
+namespace phosg {
+
+std::unique_ptr<FILE, void (*)(FILE*)> popen_unique(const std::string& command, const std::string& mode);
 
 std::string name_for_pid(pid_t pid);
 pid_t pid_for_name(const std::string& name, bool search_commands = true, bool exclude_self = true);
@@ -89,3 +90,5 @@ SubprocessResult run_process(const std::vector<std::string>& cmd,
     const std::string* cwd = nullptr,
     const std::unordered_map<std::string, std::string>* env = nullptr,
     size_t timeout_secs = 0);
+
+} // namespace phosg
diff --git a/src/ProcessTest.cc b/src/ProcessTest.cc
index a807611..8209db6 100644
--- a/src/ProcessTest.cc
+++ b/src/ProcessTest.cc
@@ -16,6 +16,7 @@
 #include "UnitTest.hh"
 
 using namespace std;
+using namespace phosg;
 
 #ifndef PHOSG_WINDOWS
 
diff --git a/src/Random.cc b/src/Random.cc
index 45bdc5c..ccd3cc8 100644
--- a/src/Random.cc
+++ b/src/Random.cc
@@ -11,6 +11,8 @@
 
 using namespace std;
 
+namespace phosg {
+
 string random_data(size_t bytes) {
   string ret(bytes, '\0');
   random_data(ret.data(), ret.size());
@@ -46,3 +48,5 @@ int64_t random_int(int64_t low, int64_t high) {
     return low + (random_object<uint8_t>() % range);
   }
 }
+
+} // namespace phosg
diff --git a/src/Random.hh b/src/Random.hh
index 885b320..a41942c 100644
--- a/src/Random.hh
+++ b/src/Random.hh
@@ -5,6 +5,8 @@
 
 #include <string>
 
+namespace phosg {
+
 std::string random_data(size_t bytes);
 void random_data(void* data, size_t bytes);
 
@@ -16,3 +18,5 @@ T random_object() {
 }
 
 int64_t random_int(int64_t low, int64_t high);
+
+} // namespace phosg
diff --git a/src/Strings.cc b/src/Strings.cc
index 2c23738..118e2a7 100644
--- a/src/Strings.cc
+++ b/src/Strings.cc
@@ -22,6 +22,8 @@
 
 using namespace std;
 
+namespace phosg {
+
 unique_ptr<void, void (*)(void*)> malloc_unique(size_t size) {
   return unique_ptr<void, void (*)(void*)>(malloc(size), free);
 }
@@ -44,7 +46,7 @@ string toupper(const string& s) {
   string ret;
   ret.reserve(s.size());
   for (char ch : s) {
-    ret.push_back(toupper(ch));
+    ret.push_back(::toupper(ch));
   }
   return ret;
 }
@@ -53,7 +55,7 @@ string tolower(const string& s) {
   string ret;
   ret.reserve(s.size());
   for (char ch : s) {
-    ret.push_back(tolower(ch));
+    ret.push_back(::tolower(ch));
   }
   return ret;
 }
@@ -1763,3 +1765,5 @@ void BlockStringWriter::write_vprintf(const char* fmt, va_list va) {
 string BlockStringWriter::close(const char* separator) {
   return join(this->blocks, separator);
 }
+
+} // namespace phosg
diff --git a/src/Strings.hh b/src/Strings.hh
index 289ecc0..f8fef64 100644
--- a/src/Strings.hh
+++ b/src/Strings.hh
@@ -15,6 +15,8 @@
 #include "Filesystem.hh"
 #include "Platform.hh"
 
+namespace phosg {
+
 std::unique_ptr<void, void (*)(void*)> malloc_unique(size_t size);
 
 bool starts_with(const std::string& s, const std::string& start);
@@ -810,3 +812,5 @@ T* data_at(std::string& s, size_t offset = 0) {
 }
 
 size_t count_zeroes(const void* vdata, size_t size, size_t stride = 1);
+
+} // namespace phosg
diff --git a/src/StringsTest.cc b/src/StringsTest.cc
index aa13c6b..a87c310 100644
--- a/src/StringsTest.cc
+++ b/src/StringsTest.cc
@@ -8,6 +8,7 @@
 #include "UnitTest.hh"
 
 using namespace std;
+using namespace phosg;
 
 template <typename... ArgTs>
 void print_data_test_case(const string& expected_output, ArgTs... args) {
diff --git a/src/Time.cc b/src/Time.cc
index 95db7e1..51f8edf 100644
--- a/src/Time.cc
+++ b/src/Time.cc
@@ -10,6 +10,8 @@
 
 using namespace std;
 
+namespace phosg {
+
 uint64_t now() {
   timeval t;
   gettimeofday(&t, nullptr);
@@ -118,3 +120,5 @@ struct timeval usecs_to_timeval(uint64_t usecs) {
 uint64_t timeval_to_usecs(struct timeval& tv) {
   return (tv.tv_sec * 1000000) + tv.tv_usec;
 }
+
+} // namespace phosg
diff --git a/src/Time.hh b/src/Time.hh
index 21e3834..e509995 100644
--- a/src/Time.hh
+++ b/src/Time.hh
@@ -4,6 +4,8 @@
 
 #include <string>
 
+namespace phosg {
+
 uint64_t now();
 
 std::string format_time(uint64_t t);
@@ -12,3 +14,5 @@ std::string format_duration(uint64_t usecs, int8_t subsecond_precision = -1);
 
 struct timeval usecs_to_timeval(uint64_t usecs);
 uint64_t timeval_to_usecs(struct timeval& tv);
+
+} // namespace phosg
diff --git a/src/TimeTest.cc b/src/TimeTest.cc
index 8e57c66..962750d 100644
--- a/src/TimeTest.cc
+++ b/src/TimeTest.cc
@@ -5,9 +5,9 @@
 #include "UnitTest.hh"
 
 using namespace std;
+using namespace phosg;
 
 int main(int, char**) {
-
   fprintf(stderr, "-- usleep\n");
   uint64_t start_time = now();
   expect_ge(now(), start_time);
diff --git a/src/Tools.cc b/src/Tools.cc
index b2c8fbf..3edb7b7 100644
--- a/src/Tools.cc
+++ b/src/Tools.cc
@@ -2,8 +2,12 @@
 
 using namespace std;
 
+namespace phosg {
+
 CallOnDestroy::CallOnDestroy(function<void()> f) : f(f) {}
 
 CallOnDestroy::~CallOnDestroy() {
   this->f();
 }
+
+} // namespace phosg
diff --git a/src/Tools.hh b/src/Tools.hh
index 95e2fbb..5859e92 100644
--- a/src/Tools.hh
+++ b/src/Tools.hh
@@ -13,6 +13,8 @@
 #include "Strings.hh"
 #include "Time.hh"
 
+namespace phosg {
+
 class CallOnDestroy {
 public:
   CallOnDestroy(std::function<void()> f);
@@ -111,3 +113,5 @@ IntT parallel_range(
 
   return result_value;
 }
+
+} // namespace phosg
diff --git a/src/ToolsTest.cc b/src/ToolsTest.cc
index ec92407..5d04eb5 100644
--- a/src/ToolsTest.cc
+++ b/src/ToolsTest.cc
@@ -4,6 +4,7 @@
 #include "UnitTest.hh"
 
 using namespace std;
+using namespace phosg;
 
 int main(int, char**) {
   printf("-- on_close_scope\n");
diff --git a/src/Types.hh b/src/Types.hh
index 82604f6..d827669 100644
--- a/src/Types.hh
+++ b/src/Types.hh
@@ -3,6 +3,8 @@
 #include <compare>
 #include <stdexcept>
 
+namespace phosg {
+
 inline std::partial_ordering partial_order_for_strong_order(std::strong_ordering st_order) {
   if (st_order < 0) {
     return std::partial_ordering::less;
@@ -29,3 +31,5 @@ const char* name_for_enum(T) {
   static_assert(always_false<T>::v, "unspecialized name_for_enum should never be called");
   throw std::logic_error("unspecialized name_for_enum should never be called");
 }
+
+} // namespace phosg
diff --git a/src/UnitTest.cc b/src/UnitTest.cc
index 5e2dffa..f3417ad 100644
--- a/src/UnitTest.cc
+++ b/src/UnitTest.cc
@@ -6,6 +6,8 @@
 
 using namespace std;
 
+namespace phosg {
+
 expectation_failed::expectation_failed(const char* msg, const char* file, uint64_t line)
     : logic_error(string_printf("failure at %s:%" PRIu64 ": %s", file, line, msg)),
       msg(msg),
@@ -34,3 +36,5 @@ void expect_raises<std::exception>(std::function<void()> fn) {
     expect_msg(false, "incorrect exception type raised");
   }
 };
+
+} // namespace phosg
diff --git a/src/UnitTest.hh b/src/UnitTest.hh
index de89b4a..59eee30 100644
--- a/src/UnitTest.hh
+++ b/src/UnitTest.hh
@@ -7,6 +7,8 @@
 
 #include "Strings.hh"
 
+namespace phosg {
+
 class expectation_failed : public std::logic_error {
 public:
   expectation_failed(const char* msg, const char* file, uint64_t line);
@@ -48,3 +50,5 @@ void expect_raises(std::function<void()> fn) {
 
 template <>
 void expect_raises<std::exception>(std::function<void()> fn);
+
+} // namespace phosg
diff --git a/src/UnitTestTest.cc b/src/UnitTestTest.cc
index 2d93c1b..9cfa65f 100644
--- a/src/UnitTestTest.cc
+++ b/src/UnitTestTest.cc
@@ -3,6 +3,7 @@
 #include "UnitTest.hh"
 
 using namespace std;
+using namespace phosg;
 
 #define expect_fails(x)                                                       \
   do {                                                                        \
diff --git a/src/Vector-inl.hh b/src/Vector-inl.hh
index ee4295c..b80edc7 100644
--- a/src/Vector-inl.hh
+++ b/src/Vector-inl.hh
@@ -6,6 +6,8 @@
 
 #include "Strings.hh"
 
+namespace phosg {
+
 template <typename T>
 Vector2<T>::Vector2()
     : x(0),
@@ -811,3 +813,5 @@ std::string Matrix4<T>::str() const {
       this->m[0][2], this->m[1][2], this->m[2][2], this->m[3][2],
       this->m[0][3], this->m[1][3], this->m[2][3], this->m[3][3]);
 }
+
+} // namespace phosg
diff --git a/src/Vector.hh b/src/Vector.hh
index 3a0cdb1..8fde407 100644
--- a/src/Vector.hh
+++ b/src/Vector.hh
@@ -2,6 +2,8 @@
 
 #include <string>
 
+namespace phosg {
+
 template <typename T>
 struct Vector2 {
   union {
@@ -211,4 +213,6 @@ struct Matrix4 {
   std::string str() const;
 };
 
+} // namespace phosg
+
 #include "Vector-inl.hh"