diff --git a/gnu/packages/gnuzilla.scm b/gnu/packages/gnuzilla.scm
index cf66958857..440d9509c1 100644
--- a/gnu/packages/gnuzilla.scm
+++ b/gnu/packages/gnuzilla.scm
@@ -1012,7 +1012,7 @@ (define-public icecat
              (let ((null-hash "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"))
                (for-each (lambda (file)
                            (format #t "patching checksums in ~a~%" file)
-                           (substitute* (find-files "." "Cargo.lock$")
+                           (substitute* file
                              (("^checksum = \".*\"")
                               (string-append "checksum = \"" null-hash "\""))))
                          (find-files "." "Cargo.lock$"))