diff --git a/dissect/clfs/c_clfs.py b/dissect/clfs/c_clfs.py
index d32bc4a..b808f76 100644
--- a/dissect/clfs/c_clfs.py
+++ b/dissect/clfs/c_clfs.py
@@ -136,7 +136,7 @@
         ULONGLONG Alignment;
     };
 
-    DWORD Image;
+    DWORD ImageSize;
     DWORD Offset;
     CLFS_METADATA_BLOCK_TYPE Type;
     DWORD Padding;
@@ -297,8 +297,7 @@
 };
 """
 
-c_clfs = cstruct()
-c_clfs.load(clfs_def)
+c_clfs = cstruct().load(clfs_def)
 
 SECTOR_SIZE = 512
 CLFS_CONTROL_RECORD_MAGIC_VALUE = 0xC1F5C1F500005F1C
diff --git a/pyproject.toml b/pyproject.toml
index 9446539..1cfa411 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -25,7 +25,7 @@ classifiers = [
   "Topic :: Utilities",
 ]
 dependencies = [
-    "dissect.cstruct>=3.0.dev,<4.0.dev",
+    "dissect.cstruct>=4.dev,<5",
 ]
 dynamic = ["version"]
 
@@ -34,6 +34,11 @@ homepage = "https://dissect.tools"
 documentation = "https://docs.dissect.tools/en/latest/projects/dissect.clfs"
 repository = "https://github.com/fox-it/dissect.clfs"
 
+[project.optional-dependencies]
+dev = [
+    "dissect.cstruct>=4.0.dev,<5.0.dev",
+]
+
 [tool.black]
 line-length = 120
 
diff --git a/tox.ini b/tox.ini
index 67e8e8a..7bd2890 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,6 +11,7 @@ minversion = 4.4.3
 requires = virtualenv>=20.16.6
 
 [testenv]
+extras = dev
 deps =
     pytest
     pytest-cov