diff --git a/pkgs/build-support/rust/build-rust-crate/helpers.nix b/pkgs/build-support/rust/build-rust-crate/helpers.nix
index 8a0a62434ec0..14d997b2d5cf 100644
--- a/pkgs/build-support/rust/build-rust-crate/helpers.nix
+++ b/pkgs/build-support/rust/build-rust-crate/helpers.nix
@@ -14,9 +14,8 @@
   include = includedFiles: src: builtins.filterSource (path: type:
      lib.lists.any (f:
        let p = toString (src + ("/" + f));
-           suff = lib.strings.removePrefix p path;
        in
-       suff == "" || (lib.strings.hasPrefix "/" suff)
+       p == path || (lib.strings.hasPrefix (p + "/") path)
      ) includedFiles
   ) src;
   exclude = excludedFiles: src: builtins.filterSource (path: type: