diff --git a/lib/libtdekrb/configure.in.in b/lib/libtdekrb/configure.in.in
index 18b1486..aa370f6 100644
--- a/lib/libtdekrb/configure.in.in
+++ b/lib/libtdekrb/configure.in.in
@@ -4,3 +4,4 @@ AM_INIT_AUTOMAKE(autostart, 0.1)
 AC_C_BIGENDIAN
 AC_CHECK_KDEMAXPATHLEN
 
+CXXFLAGS="-DQT_CLEAN_NAMESPACE $CXXFLAGS"