diff --git a/unittests/ADT/StringRefTest.cpp b/unittests/ADT/StringRefTest.cpp
index 887ba5d..de5c349 100644
--- a/unittests/ADT/StringRefTest.cpp
+++ b/unittests/ADT/StringRefTest.cpp
@@ -53,6 +53,14 @@
   EXPECT_EQ( 1, StringRef("aab").compare("aaa"));
   EXPECT_EQ(-1, StringRef("aab").compare("aabb"));
   EXPECT_EQ( 1, StringRef("aab").compare("aa"));
+  EXPECT_EQ( 1, StringRef("\xFF").compare("\1"));
+
+  EXPECT_EQ(-1, StringRef("AaB").compare_lower("aAd"));
+  EXPECT_EQ( 0, StringRef("AaB").compare_lower("aab"));
+  EXPECT_EQ( 1, StringRef("AaB").compare_lower("AAA"));
+  EXPECT_EQ(-1, StringRef("AaB").compare_lower("aaBb"));
+  EXPECT_EQ( 1, StringRef("AaB").compare_lower("aA"));
+  EXPECT_EQ( 1, StringRef("\xFF").compare_lower("\1"));
 
   EXPECT_EQ(-1, StringRef("aab").compare_numeric("aad"));
   EXPECT_EQ( 0, StringRef("aab").compare_numeric("aab"));