diff --git a/mkspecs/aix-xlc/qmake.conf b/mkspecs/aix-xlc/qmake.conf
index 163e534ff30..8ea3d57299f 100644
--- a/mkspecs/aix-xlc/qmake.conf
+++ b/mkspecs/aix-xlc/qmake.conf
@@ -21,7 +21,7 @@ QMAKE_CFLAGS_DEBUG	= -g
 QMAKE_CFLAGS_SHLIB	=
 QMAKE_CFLAGS_STATIC_LIB	= $$QMAKE_CFLAGS_SHLIB
 QMAKE_CFLAGS_YACC	=
-QMAKE_CFLAGS_THREAD	= -qthreaded
+QMAKE_CFLAGS_THREAD	= -qthreaded -qtls
 
 QMAKE_CXX		= xlC
 QMAKE_CXX_THREAD	= xlC_r