diff --git a/panda/src/collide/collisionPolygon.cxx b/panda/src/collide/collisionPolygon.cxx
index 91123028f7..f130b3061b 100644
--- a/panda/src/collide/collisionPolygon.cxx
+++ b/panda/src/collide/collisionPolygon.cxx
@@ -40,6 +40,7 @@
 #include "geomTrifans.h"
 #include "geomLinestrips.h"
 #include "geomVertexWriter.h"
+#include "renderState.h"
 
 #include <algorithm>