diff --git a/pkgs/by-name/ae/aegisub/package.nix b/pkgs/by-name/ae/aegisub/package.nix
index a6d7b5e90692..7107d548410d 100644
--- a/pkgs/by-name/ae/aegisub/package.nix
+++ b/pkgs/by-name/ae/aegisub/package.nix
@@ -134,7 +134,7 @@ stdenv.mkDerivation (finalAttrs: {
   # error: unknown type name 'NSUInteger'
   postPatch = ''
     substituteInPlace src/dialog_colorpicker.cpp \
-      --replace "NSUInteger" "size_t"
+      --replace-fail "NSUInteger" "size_t"
   '';
 
   env = {