diff --git a/cmdline/selftest.c b/cmdline/selftest.c
index b0cd9daa..5d7b8f65 100644
--- a/cmdline/selftest.c
+++ b/cmdline/selftest.c
@@ -267,6 +267,7 @@ static struct crc_test_vector TEST_CRC32C[] = {
 	{ "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff", 32, 0x62a8ab43 },
 	{ "\x1f\x1e\x1d\x1c\x1b\x1a\x19\x18\x17\x16\x15\x14\x13\x12\x11\x10\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00", 32, 0x113fdb5c },
 	{ "\x01\xc0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x14\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x14\x00\x00\x00\x18\x28\x00\x00\x00\x00\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00", 48, 0xd9963a56 },
+	{ "\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f", 16, 0xd9c908eb },
 	{ "\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f", 32, 0x46dd794e },
 	{ "\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21\x22\x23\x24\x25\x26\x27\x28", 40, 0x0e2c157f },
 	{ "\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\x3e\x3f\x40\x41\x42\x43\x44\x45\x46\x47\x48\x49\x4a\x4b\x4c\x4d\x4e\x4f\x50", 40, 0xe980ebf6 },
diff --git a/cmdline/util.h b/cmdline/util.h
index 3b6a3abb..9db2c402 100644
--- a/cmdline/util.h
+++ b/cmdline/util.h
@@ -146,23 +146,62 @@ static inline uint32_t crc32c_x86_plain(uint32_t crc, const unsigned char* ptr,
 {
 #ifdef CONFIG_X86_64
 	uint64_t crc64 = crc;
-	while (size >= 8) {
+
+	/* block hashes are normally 16 bytes and dominate content serialization */
+	if (tommy_likely(size == 16)) {
+		asm ("crc32q %1, %0\n" : "+r" (crc64) : "m" (*(const uint64_t*)ptr));
+		asm ("crc32q %1, %0\n" : "+r" (crc64) : "m" (*(const uint64_t*)(ptr + 8)));
+		return (uint32_t)crc64;
+	}
+
+	while (size >= 32) {
+		asm ("crc32q %1, %0\n" : "+r" (crc64) : "m" (*(const uint64_t*)ptr));
+		asm ("crc32q %1, %0\n" : "+r" (crc64) : "m" (*(const uint64_t*)(ptr + 8)));
+		asm ("crc32q %1, %0\n" : "+r" (crc64) : "m" (*(const uint64_t*)(ptr + 16)));
+		asm ("crc32q %1, %0\n" : "+r" (crc64) : "m" (*(const uint64_t*)(ptr + 24)));
+		ptr += 32;
+		size -= 32;
+	}
+	if (size >= 16) {
+		asm ("crc32q %1, %0\n" : "+r" (crc64) : "m" (*(const uint64_t*)ptr));
+		asm ("crc32q %1, %0\n" : "+r" (crc64) : "m" (*(const uint64_t*)(ptr + 8)));
+		ptr += 16;
+		size -= 16;
+	}
+	if (size >= 8) {
 		asm ("crc32q %1, %0\n" : "+r" (crc64) : "m" (*(const uint64_t*)ptr));
 		ptr += 8;
 		size -= 8;
 	}
 	crc = (uint32_t)crc64;
 #else
-	while (size >= 4) {
+	while (size >= 16) {
+		asm ("crc32l %1, %0\n" : "+r" (crc) : "m" (*(const uint32_t*)ptr));
+		asm ("crc32l %1, %0\n" : "+r" (crc) : "m" (*(const uint32_t*)(ptr + 4)));
+		asm ("crc32l %1, %0\n" : "+r" (crc) : "m" (*(const uint32_t*)(ptr + 8)));
+		asm ("crc32l %1, %0\n" : "+r" (crc) : "m" (*(const uint32_t*)(ptr + 12)));
+		ptr += 16;
+		size -= 16;
+	}
+	if (size >= 8) {
+		asm ("crc32l %1, %0\n" : "+r" (crc) : "m" (*(const uint32_t*)ptr));
+		asm ("crc32l %1, %0\n" : "+r" (crc) : "m" (*(const uint32_t*)(ptr + 4)));
+		ptr += 8;
+		size -= 8;
+	}
+#endif
+	if (size >= 4) {
 		asm ("crc32l %1, %0\n" : "+r" (crc) : "m" (*(const uint32_t*)ptr));
 		ptr += 4;
 		size -= 4;
 	}
-#endif
-	while (size) {
+	if (size >= 2) {
+		asm ("crc32w %1, %0\n" : "+r" (crc) : "m" (*(const uint16_t*)ptr));
+		ptr += 2;
+		size -= 2;
+	}
+	if (size) {
 		asm ("crc32b %1, %0\n" : "+r" (crc) : "m" (*ptr));
-		++ptr;
-		--size;
 	}
 
 	return crc;