diff --git a/libraries/physics/src/ShapeManager.cpp b/libraries/physics/src/ShapeManager.cpp
index ef7a4a1749..cb37b0f96d 100644
--- a/libraries/physics/src/ShapeManager.cpp
+++ b/libraries/physics/src/ShapeManager.cpp
@@ -57,7 +57,14 @@ bool ShapeManager::releaseShapeByKey(const HashKey& key) {
         if (shapeRef->refCount > 0) {
             shapeRef->refCount--;
             if (shapeRef->refCount == 0) {
-                _pendingGarbage.push_back(key);
+                // look for existing entry in _pendingGarbage, starting from the back
+                for (int32_t i = _pendingGarbage.size() - 1; i > -1; --i) {
+                    if (_pendingGarbage[i] == key.getHash64()) {
+                        // already on the list, don't add it again
+                        return true;
+                    }
+                }
+                _pendingGarbage.push_back(key.getHash64());
                 const int MAX_SHAPE_GARBAGE_CAPACITY = 255;
                 if (_pendingGarbage.size() > MAX_SHAPE_GARBAGE_CAPACITY) {
                     collectGarbage();
@@ -89,7 +96,7 @@ bool ShapeManager::releaseShape(const btCollisionShape* shape) {
 void ShapeManager::collectGarbage() {
     int numShapes = _pendingGarbage.size();
     for (int i = 0; i < numShapes; ++i) {
-        HashKey& key = _pendingGarbage[i];
+        HashKey key(_pendingGarbage[i]);
         ShapeReference* shapeRef = _shapeMap.find(key);
         if (shapeRef && shapeRef->refCount == 0) {
             ShapeFactory::deleteShape(shapeRef->shape);
diff --git a/libraries/physics/src/ShapeManager.h b/libraries/physics/src/ShapeManager.h
index d75bb1dc4a..58f1b53c18 100644
--- a/libraries/physics/src/ShapeManager.h
+++ b/libraries/physics/src/ShapeManager.h
@@ -75,7 +75,7 @@ private:
 
     // btHashMap is required because it supports memory alignment of the btCollisionShapes
     btHashMap<HashKey, ShapeReference> _shapeMap;
-    btAlignedObjectArray<HashKey> _pendingGarbage;
+    btAlignedObjectArray<uint64_t> _pendingGarbage;
 };
 
 #endif // hifi_ShapeManager_h
diff --git a/libraries/shared/src/HashKey.h b/libraries/shared/src/HashKey.h
index 5fce182084..a32a8664a7 100644
--- a/libraries/shared/src/HashKey.h
+++ b/libraries/shared/src/HashKey.h
@@ -32,6 +32,9 @@ class HashKey {
 public:
     static float getNumQuantizedValuesPerMeter();
 
+    HashKey() {}
+    HashKey(uint64_t hash) : _hash(hash) {}
+
     // These two methods are required by btHashMap.
     bool equals(const HashKey& other) const { return _hash == other._hash; }
     int32_t getHash() const { return (int32_t)((uint32_t)_hash); }