diff --git a/dtool/src/interrogate/interfaceMakerPythonNative.cxx b/dtool/src/interrogate/interfaceMakerPythonNative.cxx
index d10722f68a..632e49c125 100644
--- a/dtool/src/interrogate/interfaceMakerPythonNative.cxx
+++ b/dtool/src/interrogate/interfaceMakerPythonNative.cxx
@@ -32,6 +32,7 @@
 #include "cppStructType.h"
 #include "cppExpression.h"
 #include "cppParameterList.h"
+#include "cppReferenceType.h"
 #include "lineStream.h"
 
 #include <algorithm>