diff --git a/src/liblzma/common/memcmplen.h b/src/liblzma/common/memcmplen.h
index 5a481a02..5372cfa8 100644
--- a/src/liblzma/common/memcmplen.h
+++ b/src/liblzma/common/memcmplen.h
@@ -89,7 +89,8 @@ lzma_memcmplen(const uint8_t *buf1, const uint8_t *buf2,
 	// version isn't used on x86-64.
 #	define LZMA_MEMCMPLEN_EXTRA 16
 	while (len < limit) {
-		const uint32_t x = 0xFFFF ^ _mm_movemask_epi8(_mm_cmpeq_epi8(
+		const uint32_t x = 0xFFFF ^ (uint32_t)_mm_movemask_epi8(
+			_mm_cmpeq_epi8(
 			_mm_loadu_si128((const __m128i *)(buf1 + len)),
 			_mm_loadu_si128((const __m128i *)(buf2 + len))));