diff --git a/pkgs/by-name/_2/_20kly/package.nix b/pkgs/by-name/_2/_20kly/package.nix
index 605def822c2c..cb5e307ba6fc 100644
--- a/pkgs/by-name/_2/_20kly/package.nix
+++ b/pkgs/by-name/_2/_20kly/package.nix
@@ -19,7 +19,7 @@ python3Packages.buildPythonApplication (finalAttrs: {
 
   patchPhase = ''
     substituteInPlace lightyears \
-      --replace \
+      --replace-fail \
         "LIGHTYEARS_DIR = \".\"" \
         "LIGHTYEARS_DIR = \"$out/share\""
   '';