diff --git a/mkspecs/features/win32/thread.prf b/mkspecs/features/win32/thread.prf
index 76354a82002..fc832a0990e 100644
--- a/mkspecs/features/win32/thread.prf
+++ b/mkspecs/features/win32/thread.prf
@@ -1,8 +1,4 @@
 CONFIG -= thread_off
-qt {
-  target_qt:PRL_EXPORT_DEFINES += QT_THREAD_SUPPORT
-  else:DEFINES += QT_THREAD_SUPPORT
-}
 
 # #### These need to go
 debug {