diff --git a/libraries/physics/src/PhysicsEngine.cpp b/libraries/physics/src/PhysicsEngine.cpp
index 94787c0b12..2dd1140e45 100644
--- a/libraries/physics/src/PhysicsEngine.cpp
+++ b/libraries/physics/src/PhysicsEngine.cpp
@@ -855,7 +855,7 @@ void PhysicsEngine::addContactAddedCallback(PhysicsEngine::ContactAddedCallback
 }
 
 void PhysicsEngine::removeContactAddedCallback(PhysicsEngine::ContactAddedCallback cb) {
-    int32_t numCallbacks = _contactAddedCallbacks.size();
+    int32_t numCallbacks = (int32_t)(_contactAddedCallbacks.size());
     for (int32_t i = 0; i < numCallbacks; ++i) {
         if (_contactAddedCallbacks[i] == cb) {
             // found it --> remove it