diff --git a/pkgs/by-name/ml/mlt/package.nix b/pkgs/by-name/ml/mlt/package.nix
index db580fba2944..4d07ef764a36 100644
--- a/pkgs/by-name/ml/mlt/package.nix
+++ b/pkgs/by-name/ml/mlt/package.nix
@@ -152,7 +152,7 @@ stdenv.mkDerivation (finalAttrs: {
 
   postFixup = ''
     substituteInPlace "$dev"/lib/pkgconfig/mlt-framework-7.pc \
-      --replace '=''${prefix}//' '=/'
+      --replace-fail '=''${prefix}//' '=/'
   '';
 
   passthru = {