diff --git a/src/utilities/__tests__/buildASTSchema-test.js b/src/utilities/__tests__/buildASTSchema-test.js
index f8df76bb0a..13dba97e8d 100644
--- a/src/utilities/__tests__/buildASTSchema-test.js
+++ b/src/utilities/__tests__/buildASTSchema-test.js
@@ -116,6 +116,7 @@ describe('Schema Builder', () => {
       }
     `);
 
+    // String and Boolean are always included through introspection types
     expect(schema.getType('Int')).to.equal(undefined);
     expect(schema.getType('Float')).to.equal(undefined);
     expect(schema.getType('ID')).to.equal(undefined);
diff --git a/src/utilities/__tests__/extendSchema-test.js b/src/utilities/__tests__/extendSchema-test.js
index c66a14403b..d259269459 100644
--- a/src/utilities/__tests__/extendSchema-test.js
+++ b/src/utilities/__tests__/extendSchema-test.js
@@ -277,6 +277,7 @@ describe('extendSchema', () => {
       }
     `);
 
+    // String and Boolean are always included through introspection types
     expect(schema.getType('Int')).to.equal(undefined);
     expect(schema.getType('Float')).to.equal(undefined);
     expect(schema.getType('String')).to.equal(GraphQLString);