diff --git a/common/helpers/diff_test.go b/common/helpers/diff_test.go
new file mode 100644
index 00000000..19d6d935
--- /dev/null
+++ b/common/helpers/diff_test.go
@@ -0,0 +1,26 @@
+// SPDX-FileCopyrightText: 2025 Free Mobile
+// SPDX-License-Identifier: AGPL-3.0-only
+
+package helpers
+
+import "testing"
+
+func TestDiffStringBytes(t *testing.T) {
+	type TestStruct struct {
+		A any
+		B any
+	}
+	got := TestStruct{
+		A: "hello",
+		B: []byte("bye"),
+	}
+	want := TestStruct{
+		A: "hello",
+		B: "bye",
+	}
+	if diff := Diff(got, want); diff == "" {
+		// We expect a diff if we have []byte in one case and string in another.
+		// The test is mostly for self-documentation of this behavior.
+		t.Fatalf("Diff() (-got, +want):\n%s", diff)
+	}
+}