diff --git a/include/llvm/Support/ScaledNumber.h b/include/llvm/Support/ScaledNumber.h
index 6a93623a8e9..240d5b64aa8 100644
--- a/include/llvm/Support/ScaledNumber.h
+++ b/include/llvm/Support/ScaledNumber.h
@@ -242,6 +242,8 @@ int compareImpl(uint64_t L, uint64_t R, int ScaleDiff);
 /// for greater than.
 template <class DigitsT>
 int compare(DigitsT LDigits, int16_t LScale, DigitsT RDigits, int16_t RScale) {
+  static_assert(!std::numeric_limits<DigitsT>::is_signed, "expected unsigned");
+
   // Check for zero.
   if (!LDigits)
     return RDigits ? -1 : 0;
diff --git a/unittests/Support/ScaledNumberTest.cpp b/unittests/Support/ScaledNumberTest.cpp
index f6d7a44754f..4a274d7e50e 100644
--- a/unittests/Support/ScaledNumberTest.cpp
+++ b/unittests/Support/ScaledNumberTest.cpp
@@ -285,7 +285,7 @@ TEST(ScaledNumberHelpersTest, getLgCeiling) {
   EXPECT_EQ(INT32_MIN, getLgCeiling(UINT64_C(0), 1));
 }
 
-TEST(ScaledNumberHelpersTest, Compare) {
+TEST(ScaledNumberHelpersTest, compare) {
   EXPECT_EQ(0, compare(UINT32_C(0), 0, UINT32_C(0), 1));
   EXPECT_EQ(0, compare(UINT32_C(0), 0, UINT32_C(0), -10));
   EXPECT_EQ(0, compare(UINT32_C(0), 0, UINT32_C(0), 20));