diff --git a/pkgs/build-support/rust/fetch-cargo-deps b/pkgs/build-support/rust/fetch-cargo-deps
index 04d33c60d30..b119be273ba 100755
--- a/pkgs/build-support/rust/fetch-cargo-deps
+++ b/pkgs/build-support/rust/fetch-cargo-deps
@@ -172,3 +172,8 @@ done)
 # Remove unneeded outputs
 [[ ! -d $out/registry/src ]] || rm -rf $out/registry/src
 [[ ! -d $out/git/checkouts ]] || rm -rf $out/git/checkouts
+
+# XXX: provide some debugging output to see find out why we are seeing
+# sporadic hash mismatches
+find $out ! -type f
+find $out -type f -exec sha256sum {} +