diff --git a/libc/intrin/bswap.c b/libc/intrin/bswap.c
index 1b6816922..66475aa52 100644
--- a/libc/intrin/bswap.c
+++ b/libc/intrin/bswap.c
@@ -45,3 +45,8 @@ uint64_t(bswap_64)(uint64_t x) {
          (0x00ff000000000000ull & x) >> 050 |
          (0xff00000000000000ull & x) >> 070;
 }
+
+uint128_t(bswap_128)(uint128_t x) {
+  return ((uint128_t)bswap_64((uint64_t)x) << 64) |
+         (uint128_t)bswap_64((uint64_t)(x >> 64));
+}
diff --git a/libc/intrin/bswap.h b/libc/intrin/bswap.h
index 05f55629d..a16095816 100644
--- a/libc/intrin/bswap.h
+++ b/libc/intrin/bswap.h
@@ -5,11 +5,13 @@ COSMOPOLITAN_C_START_
 libcesque uint16_t bswap_16(uint16_t) pureconst;
 libcesque uint32_t bswap_32(uint32_t) pureconst;
 libcesque uint64_t bswap_64(uint64_t) pureconst;
+libcesque uint128_t bswap_128(uint128_t) pureconst;
 
 #if defined(__GNUC__) && !defined(__STRICT_ANSI__)
-#define bswap_16(x) __builtin_bswap16(x)
-#define bswap_32(x) __builtin_bswap32(x)
-#define bswap_64(x) __builtin_bswap64(x)
+#define bswap_16(x)  __builtin_bswap16(x)
+#define bswap_32(x)  __builtin_bswap32(x)
+#define bswap_64(x)  __builtin_bswap64(x)
+#define bswap_128(x) __builtin_bswap128(x)
 #endif /* defined(__GNUC__) && !defined(__STRICT_ANSI__) */
 
 COSMOPOLITAN_C_END_
diff --git a/libc/intrin/newbie.h b/libc/intrin/newbie.h
index 46528b0ae..65fcd797d 100644
--- a/libc/intrin/newbie.h
+++ b/libc/intrin/newbie.h
@@ -8,43 +8,55 @@
 #define PDP_ENDIAN    __ORDER_PDP_ENDIAN__
 
 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
-#define htobe16(x) bswap_16(x)
-#define be16toh(x) bswap_16(x)
-#define betoh16(x) bswap_16(x)
-#define htobe32(x) bswap_32(x)
-#define be32toh(x) bswap_32(x)
-#define betoh32(x) bswap_32(x)
-#define htobe64(x) bswap_64(x)
-#define be64toh(x) bswap_64(x)
-#define betoh64(x) bswap_64(x)
-#define htole16(x) (uint16_t)(x)
-#define le16toh(x) (uint16_t)(x)
-#define letoh16(x) (uint16_t)(x)
-#define htole32(x) (uint32_t)(x)
-#define le32toh(x) (uint32_t)(x)
-#define letoh32(x) (uint32_t)(x)
-#define htole64(x) (uint64_t)(x)
-#define le64toh(x) (uint64_t)(x)
-#define letoh64(x) (uint64_t)(x)
+#define htobe16(x)  bswap_16(x)
+#define be16toh(x)  bswap_16(x)
+#define betoh16(x)  bswap_16(x)
+#define htobe32(x)  bswap_32(x)
+#define be32toh(x)  bswap_32(x)
+#define betoh32(x)  bswap_32(x)
+#define htobe64(x)  bswap_64(x)
+#define be64toh(x)  bswap_64(x)
+#define betoh64(x)  bswap_64(x)
+#define htobe128(x) bswap_128(x)
+#define be128toh(x) bswap_128(x)
+#define betoh128(x) bswap_128(x)
+#define htole16(x)  (uint16_t)(x)
+#define le16toh(x)  (uint16_t)(x)
+#define letoh16(x)  (uint16_t)(x)
+#define htole32(x)  (uint32_t)(x)
+#define le32toh(x)  (uint32_t)(x)
+#define letoh32(x)  (uint32_t)(x)
+#define htole64(x)  (uint64_t)(x)
+#define le64toh(x)  (uint64_t)(x)
+#define letoh64(x)  (uint64_t)(x)
+#define htole128(x) (uint128_t)(x)
+#define le128toh(x) (uint128_t)(x)
+#define letoh128(x) (uint128_t)(x)
 #else
-#define htobe16(x) (uint16_t)(x)
-#define be16toh(x) (uint16_t)(x)
-#define betoh16(x) (uint16_t)(x)
-#define htobe32(x) (uint32_t)(x)
-#define be32toh(x) (uint32_t)(x)
-#define betoh32(x) (uint32_t)(x)
-#define htobe64(x) (uint64_t)(x)
-#define be64toh(x) (uint64_t)(x)
-#define betoh64(x) (uint64_t)(x)
-#define htole16(x) bswap_16(x)
-#define le16toh(x) bswap_16(x)
-#define letoh16(x) bswap_16(x)
-#define htole32(x) bswap_32(x)
-#define le32toh(x) bswap_32(x)
-#define letoh32(x) bswap_32(x)
-#define htole64(x) bswap_64(x)
-#define le64toh(x) bswap_64(x)
-#define letoh64(x) bswap_64(x)
+#define htobe16(x)  (uint16_t)(x)
+#define be16toh(x)  (uint16_t)(x)
+#define betoh16(x)  (uint16_t)(x)
+#define htobe32(x)  (uint32_t)(x)
+#define be32toh(x)  (uint32_t)(x)
+#define betoh32(x)  (uint32_t)(x)
+#define htobe64(x)  (uint64_t)(x)
+#define be64toh(x)  (uint64_t)(x)
+#define betoh64(x)  (uint64_t)(x)
+#define htobe128(x) (uint128_t)(x)
+#define be128toh(x) (uint128_t)(x)
+#define betoh128(x) (uint128_t)(x)
+#define htole16(x)  bswap_16(x)
+#define le16toh(x)  bswap_16(x)
+#define letoh16(x)  bswap_16(x)
+#define htole32(x)  bswap_32(x)
+#define le32toh(x)  bswap_32(x)
+#define letoh32(x)  bswap_32(x)
+#define htole64(x)  bswap_64(x)
+#define le64toh(x)  bswap_64(x)
+#define letoh64(x)  bswap_64(x)
+#define htole128(x) bswap_128(x)
+#define le128toh(x) bswap_128(x)
+#define letoh128(x) bswap_128(x)
 #endif
 
 #endif /* COSMOPOLITAN_LIBC_BITS_NEWBIE_H_ */