diff --git a/pkgs/build-support/make-startupitem/default.nix b/pkgs/build-support/make-startupitem/default.nix
index 03677355b8d6..b1294a43a0f8 100644
--- a/pkgs/build-support/make-startupitem/default.nix
+++ b/pkgs/build-support/make-startupitem/default.nix
@@ -32,7 +32,7 @@ stdenv.mkDerivation {
       target=${name}.desktop
       cp ${package}/share/applications/${srcPrefix}${name}.desktop $target
       ${lib.optionalString (prependExtraArgs != [ ] || appendExtraArgs != [ ]) ''
-        sed -i -r "s/(Exec=)([^ \n]*) *(.*)/\1\2 ${prependArgs}\3${appendArgs}/" $target
+        sed -i -r "s/^(Exec=)([^ \n]*) *(.*)/\1\2 ${prependArgs}\3${appendArgs}/" $target
       ''}
       chmod +rw $target
       echo "X-KDE-autostart-phase=${phase}" >> $target