diff --git a/pkgs/desktops/kde-5/plasma/plasma-desktop/default.nix b/pkgs/desktops/kde-5/plasma/plasma-desktop/default.nix
index dc4e81ef4eaa..e2b1acd198f9 100644
--- a/pkgs/desktops/kde-5/plasma/plasma-desktop/default.nix
+++ b/pkgs/desktops/kde-5/plasma/plasma-desktop/default.nix
@@ -36,6 +36,6 @@ plasmaPackage rec {
   NIX_CFLAGS_COMPILE = [ "-I${xorgserver.dev}/include/xorg" ];
   cmakeFlags = [
     "-DEvdev_INCLUDE_DIRS=${xf86inputevdev.dev}/include/xorg"
-    "-DSynaptics_INCLUDE_DIRS=${xf86inputsynaptics}/include/xorg"
+    "-DSynaptics_INCLUDE_DIRS=${xf86inputsynaptics.dev}/include/xorg"
   ];
 }