diff --git a/pkgs/applications/emulators/retroarch/cores.nix b/pkgs/applications/emulators/retroarch/cores.nix
index d67ae6b5318e..d1cbf12b34d0 100644
--- a/pkgs/applications/emulators/retroarch/cores.nix
+++ b/pkgs/applications/emulators/retroarch/cores.nix
@@ -768,7 +768,7 @@ in
     # causes redefinition of _FORTIFY_SOURCE
     hardeningDisable = [ "fortify3" ];
 
-    postBuild = "cd /build/source/build/pcsx2";
+    postBuild = "cd $NIX_BUILD_TOP/source/build/pcsx2";
     meta = {
       description = "Port of PCSX2 to libretro";
       license = lib.licenses.gpl3Plus;