diff --git a/tide/normalize.go b/tide/normalize.go
index 1c44729..07ee71d 100644
--- a/tide/normalize.go
+++ b/tide/normalize.go
@@ -81,6 +81,9 @@ func maskDate(path string, val any, diffs *[]Diff) any {
 }
 
 func maskIDValue(path string, val any, diffs *[]Diff) any {
+	if val == nil {
+		return nil
+	}
 	n, ok := val.(json.Number)
 	if !ok {
 		*diffs = append(*diffs, Diff{Path: path, Expected: "integer id", Actual: formatValue(val)})
diff --git a/tide/normalize_test.go b/tide/normalize_test.go
index 00156e6..944de80 100644
--- a/tide/normalize_test.go
+++ b/tide/normalize_test.go
@@ -16,6 +16,10 @@ func TestNormalizeDateIDAndDisable(t *testing.T) {
 	if diffs := compareBodies(Response{Headers: jsonCT(), Body: Body(want)}, Response{Headers: jsonCT(), Body: Body(gotOK)}, step); len(diffs) != 0 {
 		t.Fatalf("masked date/id should pass: %+v", diffs)
 	}
+	nullID := []byte(`{"id":1,"discogs_id":null,"created_at":"2026-01-01T00:00:00+00:00","slug":"keep-me"}`)
+	if diffs := compareBodies(Response{Headers: jsonCT(), Body: Body(nullID)}, Response{Headers: jsonCT(), Body: Body(nullID)}, step); len(diffs) != 0 {
+		t.Fatalf("null *_id must pass: %+v", diffs)
+	}
 	zdiffs := compareBodies(Response{Headers: jsonCT(), Body: Body(want)}, Response{Headers: jsonCT(), Body: Body(gotZ)}, step)
 	if len(zdiffs) == 0 {
 		t.Fatal("Z date must fail")