diff --git a/pkgs/source_maps/test/parser_test.dart b/pkgs/source_maps/test/parser_test.dart
index 8714152..8c98c81 100644
--- a/pkgs/source_maps/test/parser_test.dart
+++ b/pkgs/source_maps/test/parser_test.dart
@@ -329,16 +329,16 @@
       MAP_WITH_SOURCE_LOCATION,
       MAP_WITH_SOURCE_LOCATION_AND_NAME
     ]) {
-      var mapping = parseJson(expected) as SingleMapping;
+      SingleMapping mapping = parseJson(expected);
       expect(mapping.toJson(), equals(expected));
 
-      mapping = parseJsonExtended(expected) as SingleMapping;
+      mapping = parseJsonExtended(expected);
       expect(mapping.toJson(), equals(expected));
     }
     // Invalid for this case
-    expect(() => parseJson(SOURCE_MAP_BUNDLE as dynamic), throws) as MappingBundle;
+    expect(() => parseJson(SOURCE_MAP_BUNDLE as dynamic), throws);
 
-    var mapping = parseJsonExtended(SOURCE_MAP_BUNDLE);
+    var mapping = parseJsonExtended(SOURCE_MAP_BUNDLE) as MappingBundle;
     expect(mapping.toJson(), equals(SOURCE_MAP_BUNDLE));
   });
 }