diff --git a/dtool/src/dtoolbase/typeRegistryNode.cxx b/dtool/src/dtoolbase/typeRegistryNode.cxx
index 228f6eb642..2a5860e834 100644
--- a/dtool/src/dtoolbase/typeRegistryNode.cxx
+++ b/dtool/src/dtoolbase/typeRegistryNode.cxx
@@ -15,6 +15,7 @@
 #include "typeRegistryNode.h"
 
 #include <algorithm>
+#include <string.h>
 
 bool TypeRegistryNode::_paranoid_inheritance = false;