diff --git a/src/fdb5/toc/TocStore.cc b/src/fdb5/toc/TocStore.cc
index f834b65bf..4a8b3c695 100644
--- a/src/fdb5/toc/TocStore.cc
+++ b/src/fdb5/toc/TocStore.cc
@@ -164,24 +164,24 @@ void TocStore::remove(const eckit::URI& uri, std::ostream& logAlways, std::ostre
     }
 }
 
-eckit::DataHandle *TocStore::getCachedHandle( const eckit::PathName &path ) const {
+eckit::DataHandle* TocStore::getCachedHandle( const eckit::PathName &path ) const {
+    std::lock_guard<std::recursive_mutex> lock(handlesMutex_);
     HandleStore::const_iterator j = handles_.find( path );
     if ( j != handles_.end() )
-        return j->second;
+        return j->second.get();
     else
         return nullptr;
 }
 
 void TocStore::closeDataHandles() {
-    for ( HandleStore::iterator j = handles_.begin(); j != handles_.end(); ++j ) {
-        eckit::DataHandle *dh = j->second;
+    std::lock_guard<std::recursive_mutex> lock(handlesMutex_);
+    for (const auto& [p, dh] : handles_) {
         dh->close();
-        delete dh;
     }
     handles_.clear();
 }
 
-eckit::DataHandle *TocStore::createFileHandle(const eckit::PathName &path) {
+std::unique_ptr<eckit::DataHandle> TocStore::createFileHandle(const eckit::PathName &path) {
 
     static size_t sizeBuffer = eckit::Resource<unsigned long>("fdbBufferSize", 64 * 1024 * 1024);
 
@@ -191,17 +191,17 @@ eckit::DataHandle *TocStore::createFileHandle(const eckit::PathName &path) {
                                      << " buffer size " << sizeBuffer
                                      << std::endl;
 
-        return new LustreFileHandle<FDBFileHandle>(path, sizeBuffer, stripeDataLustreSettings());
+        return std::unique_ptr<eckit::DataHandle>(new LustreFileHandle<FDBFileHandle>(path, sizeBuffer, stripeDataLustreSettings()));
     }
 
     LOG_DEBUG_LIB(LibFdb5) << "Creating FDBFileHandle to " << path
                                  << " with buffer of " << eckit::Bytes(sizeBuffer)
                                  << std::endl;
 
-    return new FDBFileHandle(path, sizeBuffer);
+    return std::unique_ptr<eckit::DataHandle>(new FDBFileHandle(path, sizeBuffer));
 }
 
-eckit::DataHandle *TocStore::createAsyncHandle(const eckit::PathName &path) {
+std::unique_ptr<eckit::DataHandle> TocStore::createAsyncHandle(const eckit::PathName &path) {
 
     static size_t nbBuffers  = eckit::Resource<unsigned long>("fdbNbAsyncBuffers", 4);
     static size_t sizeBuffer = eckit::Resource<unsigned long>("fdbSizeAsyncBuffer", 64 * 1024 * 1024);
@@ -213,17 +213,17 @@ eckit::DataHandle *TocStore::createAsyncHandle(const eckit::PathName &path) {
                                      << " buffer each with " << eckit::Bytes(sizeBuffer)
                                      << std::endl;
 
-        return new LustreFileHandle<eckit::AIOHandle>(path, nbBuffers, sizeBuffer, stripeDataLustreSettings());
+        return std::unique_ptr<eckit::DataHandle>(new LustreFileHandle<eckit::AIOHandle>(path, nbBuffers, sizeBuffer, stripeDataLustreSettings()));
     }
 
-    return new eckit::AIOHandle(path, nbBuffers, sizeBuffer);
+    return std::unique_ptr<eckit::DataHandle>(new eckit::AIOHandle(path, nbBuffers, sizeBuffer));
 }
 
-eckit::DataHandle *TocStore::createDataHandle(const eckit::PathName &path) {
+std::unique_ptr<eckit::DataHandle> TocStore::createDataHandle(const eckit::PathName &path) {
 
     static bool fdbWriteToNull = eckit::Resource<bool>("fdbWriteToNull;$FDB_WRITE_TO_NULL", false);
     if(fdbWriteToNull)
-        return new eckit::EmptyHandle();
+        return std::unique_ptr<eckit::DataHandle>(new eckit::EmptyHandle());
 
     static bool fdbAsyncWrite = eckit::Resource<bool>("fdbAsyncWrite;$FDB_ASYNC_WRITE", false);
     if(fdbAsyncWrite)
@@ -233,12 +233,14 @@ eckit::DataHandle *TocStore::createDataHandle(const eckit::PathName &path) {
 }
 
 eckit::DataHandle& TocStore::getDataHandle( const eckit::PathName &path ) {
-    eckit::DataHandle *dh = getCachedHandle(path);
+    std::lock_guard<std::recursive_mutex> lock(handlesMutex_);
+    eckit::DataHandle* dh = getCachedHandle(path);
     if ( !dh ) {
-        dh = createDataHandle(path);
-        ASSERT(dh);
-        handles_[path] = dh;
-        dh->openForAppend(0);
+        auto dataHandle = createDataHandle(path);
+        ASSERT(dataHandle);
+        dataHandle->openForAppend(0);
+        dh = dataHandle.get();
+        handles_[path] = std::move(dataHandle);
     }
     return *dh;
 }
@@ -264,9 +266,8 @@ eckit::PathName TocStore::getDataPath(const Key& key) const {
 }
 
 void TocStore::flushDataHandles() {
-
-    for (HandleStore::iterator j = handles_.begin(); j != handles_.end(); ++j) {
-        eckit::DataHandle *dh = j->second;
+    std::lock_guard<std::recursive_mutex> lock(handlesMutex_);
+    for (const auto& [p, dh] : handles_) {
         dh->flush();
     }
 }
diff --git a/src/fdb5/toc/TocStore.h b/src/fdb5/toc/TocStore.h
index 4a28260f8..b2e0c95e8 100644
--- a/src/fdb5/toc/TocStore.h
+++ b/src/fdb5/toc/TocStore.h
@@ -67,11 +67,11 @@ class TocStore : public Store, public TocCommon {
 
     void remove(const eckit::URI& uri, std::ostream& logAlways, std::ostream& logVerbose, bool doit) const override;
 
-    eckit::DataHandle *getCachedHandle( const eckit::PathName &path ) const;
+    eckit::DataHandle* getCachedHandle( const eckit::PathName &path ) const;
     void closeDataHandles();
-    eckit::DataHandle *createFileHandle(const eckit::PathName &path);
-    eckit::DataHandle *createAsyncHandle(const eckit::PathName &path);
-    eckit::DataHandle *createDataHandle(const eckit::PathName &path);
+    std::unique_ptr<eckit::DataHandle> createFileHandle(const eckit::PathName &path);
+    std::unique_ptr<eckit::DataHandle> createAsyncHandle(const eckit::PathName &path);
+    std::unique_ptr<eckit::DataHandle> createDataHandle(const eckit::PathName &path);
     eckit::DataHandle& getDataHandle( const eckit::PathName &path );
     eckit::PathName generateDataPath(const Key& key) const;
     eckit::PathName getDataPath(const Key& key) const;
@@ -84,11 +84,12 @@ class TocStore : public Store, public TocCommon {
 
 private: // types
 
-    typedef std::map< std::string, eckit::DataHandle * >  HandleStore;
+    typedef std::map< std::string, std::unique_ptr<eckit::DataHandle>>  HandleStore;
     typedef std::map< Key, std::string > PathStore;
 
 private: // members
 
+    mutable std::recursive_mutex handlesMutex_;
     HandleStore handles_;    ///< stores the DataHandles being used by the Session
 
     mutable PathStore   dataPaths_;