diff --git a/src/BulletCollision/CollisionDispatch/btCompoundCompoundCollisionAlgorithm.h b/src/BulletCollision/CollisionDispatch/btCompoundCompoundCollisionAlgorithm.h
index 14e8a7ada..a940d840e 100644
--- a/src/BulletCollision/CollisionDispatch/btCompoundCompoundCollisionAlgorithm.h
+++ b/src/BulletCollision/CollisionDispatch/btCompoundCompoundCollisionAlgorithm.h
@@ -34,6 +34,8 @@ class btCollisionObject;
 
 class btCollisionShape;
 
+extern btShapePairCallback gCompoundCompoundChildShapePairCallback;
+
 /// btCompoundCompoundCollisionAlgorithm  supports collision between two btCompoundCollisionShape shapes
 class btCompoundCompoundCollisionAlgorithm : public btCompoundCollisionAlgorithm
 {