diff --git a/dtool/src/parser-inc/btBulletDynamicsCommon.h b/dtool/src/parser-inc/btBulletDynamicsCommon.h
index 9628556047..44bda05a04 100644
--- a/dtool/src/parser-inc/btBulletDynamicsCommon.h
+++ b/dtool/src/parser-inc/btBulletDynamicsCommon.h
@@ -49,6 +49,7 @@ class btKinematicCharacterController;
 class btManifoldPoint;
 class btMatrix3x3;
 class btMotionState;
+class btOverlapFilterCallback;
 class btPairCachingGhostObject;
 class btParalleSequentialImpulseSolver;
 class btPersistentManifold;