diff --git a/src/plugins/qt4projectmanager/qtversionmanager.cpp b/src/plugins/qt4projectmanager/qtversionmanager.cpp
index 618ad01bbb5..f07491286c8 100644
--- a/src/plugins/qt4projectmanager/qtversionmanager.cpp
+++ b/src/plugins/qt4projectmanager/qtversionmanager.cpp
@@ -1833,5 +1833,8 @@ bool QtVersion::buildDebuggingHelperLibrary(QFutureInterface<void> &future,
     }
     future.setProgressValue(4);
 
+    // invalidate cache once more
+    m_versionInfoUpToDate = false;
+
     return true;
 }