diff --git a/clang/unittests/Lex/HeaderMapTest.cpp b/clang/unittests/Lex/HeaderMapTest.cpp
index e892170..ad0579a 100644
--- a/clang/unittests/Lex/HeaderMapTest.cpp
+++ b/clang/unittests/Lex/HeaderMapTest.cpp
@@ -143,6 +143,15 @@
   ASSERT_FALSE(HeaderMapImpl::checkHeader(*File.getBuffer(), NeedsSwap));
 }
 
+TEST(HeaderMapTest, checkHeader0Buckets) {
+  // Create with 1 bucket to avoid 0-sized arrays.
+  MapFile<1, 1> File;
+  File.init();
+  File.Header.NumBuckets = 0;
+  bool NeedsSwap;
+  ASSERT_FALSE(HeaderMapImpl::checkHeader(*File.getBuffer(), NeedsSwap));
+}
+
 TEST(HeaderMapTest, checkHeaderNotEnoughBuckets) {
   MapFile<1, 1> File;
   File.init();