diff --git a/pkgs/by-name/bl/blanket/package.nix b/pkgs/by-name/bl/blanket/package.nix
index 72cb5c8faa65..a89dfeec382f 100644
--- a/pkgs/by-name/bl/blanket/package.nix
+++ b/pkgs/by-name/bl/blanket/package.nix
@@ -53,7 +53,7 @@ python3Packages.buildPythonApplication rec {
   postPatch = ''
     patchShebangs build-aux/meson/postinstall.py
     substituteInPlace build-aux/meson/postinstall.py \
-      --replace gtk-update-icon-cache gtk4-update-icon-cache
+      --replace-fail gtk-update-icon-cache gtk4-update-icon-cache
   '';
 
   dontWrapGApps = true;