diff --git a/src/GafferScene/SceneWriter.cpp b/src/GafferScene/SceneWriter.cpp
index 3ccd7d52e9..c6adac88ff 100644
--- a/src/GafferScene/SceneWriter.cpp
+++ b/src/GafferScene/SceneWriter.cpp
@@ -47,6 +47,7 @@
 #include "tbb/mutex.h"
 
 #include <filesystem>
+#include <unordered_map>
 
 using namespace std;
 using namespace IECore;