diff --git a/Framework/Kernel/inc/MantidKernel/ThreadSchedulerMutexes.h b/Framework/Kernel/inc/MantidKernel/ThreadSchedulerMutexes.h
index e14fd939289fbd4888e30776a89ee2efb03a77fb..95fbce921a059cb16da25c156e489e7425cd6231 100644
--- a/Framework/Kernel/inc/MantidKernel/ThreadSchedulerMutexes.h
+++ b/Framework/Kernel/inc/MantidKernel/ThreadSchedulerMutexes.h
@@ -64,8 +64,8 @@ public:
 
           if (!map.empty()) {
             // Look for the largest cost item in it.
-            auto it2 = mutexedMap.second.end();
-            it2--;
+            auto it2 = map.end();
+            --it2;
             // Great, we found something.
             temp = it2->second;
             // Take it out of the map (popped)