diff --git a/test/util-test.cc b/test/util-test.cc
index 8b8a20a1..59dfddff 100644
--- a/test/util-test.cc
+++ b/test/util-test.cc
@@ -699,8 +699,11 @@ void test_count_digits() {
 }
 
 TEST(UtilTest, StringRef) {
-  char space[100] = "some string";
-  EXPECT_EQ(std::strlen(space), StringRef(space).size());
+  // Test that StringRef::size() returns string length, not buffer size.
+  enum {BUFFER_SIZE = 100};
+  char str[BUFFER_SIZE] = "some string";
+  EXPECT_EQ(std::strlen(str), StringRef(str).size());
+  EXPECT_LT(std::strlen(str), BUFFER_SIZE);
 }
 
 TEST(UtilTest, CountDigits) {