diff --git a/configure.ac b/configure.ac
index 2338831b1d..b096e2e9b5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -360,7 +360,7 @@ backend_immodules=
 have_gio_unix=no
 GDK_BACKENDS=
 GDK_EXTRA_LIBS=
-GDK_EXTRA_CFLAGS="$GLIB_VERSION_CFLAGS"
+GDK_EXTRA_CFLAGS=
 GDK_WINDOWING=
 PANGO_PACKAGES="pango pangocairo"
 
@@ -500,6 +500,7 @@ else
     GTK_DEBUG_FLAGS="-DG_ENABLE_DEBUG -DG_DISABLE_CAST_CHECKS"
   fi
 fi
+GTK_DEBUG_FLAGS="$GTK_DEBUG_FLAGS $GLIB_VERSION_CFLAGS"
 
 # Build time sanity check...
 AM_SANITY_CHECK