diff --git a/pkgs/misc/screensavers/slock/default.nix b/pkgs/misc/screensavers/slock/default.nix
index 63ca76e391f4..9f364ba520cd 100644
--- a/pkgs/misc/screensavers/slock/default.nix
+++ b/pkgs/misc/screensavers/slock/default.nix
@@ -16,7 +16,7 @@ stdenv.mkDerivation rec {
 
   buildInputs = [ xorgproto libX11 libXext libXrandr ];
 
-  installFlags = [ "DESTDIR=\${out}" "PREFIX=" ];
+  installFlags = [ "PREFIX=$(out)" ];
 
   postPatch = "sed -i '/chmod u+s/d' Makefile";
 
@@ -24,6 +24,8 @@ stdenv.mkDerivation rec {
     cp ${writeText "config.def.h" conf} config.def.h
   '';
 
+  makeFlags = [ "CC:=$(CC)" ];
+
   meta = {
     homepage = "https://tools.suckless.org/slock";
     description = "Simple X display locker";