diff --git a/panda/src/bullet/bulletWorld.cxx b/panda/src/bullet/bulletWorld.cxx
index 18c23c8896..9bfa707e9d 100644
--- a/panda/src/bullet/bulletWorld.cxx
+++ b/panda/src/bullet/bulletWorld.cxx
@@ -82,7 +82,8 @@ BulletWorld() {
   _world->getPairCache()->setInternalGhostPairCallback(&_ghost_cb);
 
   // Filter callback
-  switch (bullet_filter_algorithm) {
+  _filter_algorithm = bullet_filter_algorithm;
+  switch (_filter_algorithm) {
     case FA_mask:
       _filter_cb = &_filter_cb1;
       break;
@@ -1086,7 +1087,7 @@ void BulletWorld::
 set_group_collision_flag(unsigned int group1, unsigned int group2, bool enable) {
   LightMutexHolder holder(get_global_lock());
 
-  if (bullet_filter_algorithm != FA_groups_mask) {
+  if (_filter_algorithm != FA_groups_mask) {
     bullet_cat.warning() << "filter algorithm is not 'groups-mask'" << endl;
   }
 
@@ -1198,7 +1199,7 @@ set_filter_callback(CallbackObject *obj) {
 
   nassertv(obj != NULL);
 
-  if (bullet_filter_algorithm != FA_callback) {
+  if (_filter_algorithm != FA_callback) {
     bullet_cat.warning() << "filter algorithm is not 'callback'" << endl;
   }
 
diff --git a/panda/src/bullet/bulletWorld.h b/panda/src/bullet/bulletWorld.h
index 36f3723535..35a2c8c634 100644
--- a/panda/src/bullet/bulletWorld.h
+++ b/panda/src/bullet/bulletWorld.h
@@ -265,6 +265,7 @@ private:
 
   btGhostPairCallback _ghost_cb;
 
+  FilterAlgorithm _filter_algorithm;
   btFilterCallback1 _filter_cb1;
   btFilterCallback2 _filter_cb2;
   btFilterCallback3 _filter_cb3;