diff --git a/extension-iap/src/iap_private.cpp b/extension-iap/src/iap_private.cpp
index b6ad5b9..2b90a13 100644
--- a/extension-iap/src/iap_private.cpp
+++ b/extension-iap/src/iap_private.cpp
@@ -121,13 +121,14 @@ void IAP_Queue_Push(IAPCommandQueue* queue, IAPCommand* cmd)
 void IAP_Queue_Flush(IAPCommandQueue* queue, IAPCommandFn fn, void* ctx)
 {
     assert(fn != 0);
+
+    DM_MUTEX_SCOPED_LOCK(queue->m_Mutex);
+
     if (queue->m_Commands.Empty())
     {
         return;
     }
 
-    DM_MUTEX_SCOPED_LOCK(queue->m_Mutex);
-
     for(uint32_t i = 0; i != queue->m_Commands.Size(); ++i)
     {
         fn(&queue->m_Commands[i], ctx);