diff --git a/unittests/ADT/SmallVectorTest.cpp b/unittests/ADT/SmallVectorTest.cpp
index 19ef099224d..addd904361c 100644
--- a/unittests/ADT/SmallVectorTest.cpp
+++ b/unittests/ADT/SmallVectorTest.cpp
@@ -196,7 +196,8 @@ TEST_F(SmallVectorTest, ResizeGrowTest) {
 
   theVector.resize(2);
   
-  // XXX: I don't know where the extra construct/destruct is coming from.
+  // The extra constructor/destructor calls come from the temporary object used
+  // to initialize the contents of the resized array (via copy construction).
   EXPECT_EQ(3, Constructable::getNumConstructorCalls());
   EXPECT_EQ(1, Constructable::getNumDestructorCalls());
   EXPECT_EQ(2u, theVector.size());
@@ -214,16 +215,16 @@ TEST_F(SmallVectorTest, ResizeFillTest) {
 TEST_F(SmallVectorTest, OverflowTest) {
   SCOPED_TRACE("OverflowTest");
 
-  // Push more elements than the fixed size
+  // Push more elements than the fixed size.
   makeSequence(theVector, 1, 10);
 
-  // test size and values
+  // Test size and values.
   EXPECT_EQ(10u, theVector.size());
   for (int i = 0; i < 10; ++i) {
     EXPECT_EQ(i+1, theVector[i].getValue());
   }
   
-  // Now resize back to fixed size
+  // Now resize back to fixed size.
   theVector.resize(1);
   
   assertValuesInOrder(theVector, 1u, 1);