diff --git a/core/message_queue.cpp b/core/message_queue.cpp
index 821414be07e..ce7708efe6f 100644
--- a/core/message_queue.cpp
+++ b/core/message_queue.cpp
@@ -316,12 +316,19 @@ void MessageQueue::flush() {
 
 	while (read_pos < buffer_end) {
 
-		_THREAD_SAFE_UNLOCK_
-
 		//lock on each interation, so a call can re-add itself to the message queue
 
 		Message *message = (Message *)&buffer[read_pos];
 
+		uint32_t advance = sizeof(Message);
+		if ((message->type & FLAG_MASK) != TYPE_NOTIFICATION)
+			advance += sizeof(Variant) * message->args;
+
+		//pre-advance so this function is reentrant
+		read_pos += advance;
+
+		_THREAD_SAFE_UNLOCK_
+
 		Object *target = ObjectDB::get_instance(message->instance_ID);
 
 		if (target != NULL) {
@@ -357,13 +364,9 @@ void MessageQueue::flush() {
 			}
 		}
 
-		uint32_t advance = sizeof(Message);
-		if ((message->type & FLAG_MASK) != TYPE_NOTIFICATION)
-			advance += sizeof(Variant) * message->args;
 		message->~Message();
 
 		_THREAD_SAFE_LOCK_
-		read_pos += advance;
 	}
 
 	buffer_end = 0; // reset buffer