diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 8398387094a..ab4571bfb9a 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -866,6 +866,7 @@ module ts {
 
         filename: string;
         text: string;
+
         getLineAndCharacterFromPosition(position: number): LineAndCharacter;
         getPositionFromLineAndCharacter(line: number, character: number): number;
         getLineStarts(): number[];
diff --git a/tests/cases/unittests/incrementalParser.ts b/tests/cases/unittests/incrementalParser.ts
index 5524060615e..cf6509d09ad 100644
--- a/tests/cases/unittests/incrementalParser.ts
+++ b/tests/cases/unittests/incrementalParser.ts
@@ -67,6 +67,9 @@ module ts {
         // There should be no reused nodes between two trees that are fully parsed.
         assert.isTrue(reusedElements(oldTree, newTree) === 0);
 
+        assert.equal(newTree.filename, incrementalNewTree.filename, "newTree.filename !== incrementalNewTree.filename");
+        assert.equal(newTree.text, incrementalNewTree.text, "newTree.filename !== incrementalNewTree.filename");
+
         if (expectedReusedElements !== -1) {
             var actualReusedCount = reusedElements(oldTree, incrementalNewTree);
             assert.equal(actualReusedCount, expectedReusedElements, actualReusedCount + " !== " + expectedReusedElements);