diff --git a/pkgs/development/libraries/qt-4/setup-hook.sh b/pkgs/development/libraries/qt-4/setup-hook.sh
index 9fff6e9c8ef5..6e0bbfe7f45f 100644
--- a/pkgs/development/libraries/qt-4/setup-hook.sh
+++ b/pkgs/development/libraries/qt-4/setup-hook.sh
@@ -1,5 +1,10 @@
 export QTDIR=@out@
 
-for d in @out@/include/*; do
-    export NIX_CFLAGS_COMPILE="$NIX_CFLAGS_COMPILE -I$d"
-done
+if [ -z "$normalQt" ]; then
+  # This helps for g++, but not for moc. And no qt4 package should expect
+  # having all qt4 header files dirs into -I. But the KDE nix expressions want
+  # this.
+  for d in @out@/include/*; do
+      export NIX_CFLAGS_COMPILE="$NIX_CFLAGS_COMPILE -I$d"
+  done
+fi