diff --git a/dbms/src/Common/memcmpSmall.h b/dbms/src/Common/memcmpSmall.h
index 8d69209b4ef..5dc5e04a707 100644
--- a/dbms/src/Common/memcmpSmall.h
+++ b/dbms/src/Common/memcmpSmall.h
@@ -5,13 +5,6 @@
 
 #include <Core/Defines.h>
 
-/// We can process uninitialized memory in the functions below.
-/// Results don't depend on the values inside uninitialized memory but Memory Sanitizer cannot see it.
-/// Disable optimized functions if compile with Memory Sanitizer.
-
-#if defined(__SSE2__) && !defined(MEMORY_SANITIZER)
-#include <emmintrin.h>
-
 
 namespace detail
 {
@@ -28,6 +21,15 @@ inline int cmp(T a, T b)
 
 }
 
+
+/// We can process uninitialized memory in the functions below.
+/// Results don't depend on the values inside uninitialized memory but Memory Sanitizer cannot see it.
+/// Disable optimized functions if compile with Memory Sanitizer.
+
+#if defined(__SSE2__) && !defined(MEMORY_SANITIZER)
+#include <emmintrin.h>
+
+
 /** All functions works under the following assumptions:
   * - it's possible to read up to 15 excessive bytes after end of 'a' and 'b' region;
   * - memory regions are relatively small and extra loop unrolling is not worth to do.
@@ -198,7 +200,10 @@ inline bool memoryIsZeroSmallAllowOverflow15(const void * data, size_t size)
 template <typename Char>
 inline int memcmpSmallAllowOverflow15(const Char * a, size_t a_size, const Char * b, size_t b_size)
 {
-    return memcmp(a, b, std::min(a_size, b_size));
+    if (auto res = memcmp(a, b, std::min(a_size, b_size)))
+        return res;
+    else
+        return detail::cmp(a_size, b_size);
 }
 
 template <typename Char>