diff --git a/ext/cityhash/city.cpp b/ext/cityhash/city.cpp
index c38da1e2ce..28e766b010 100644
--- a/ext/cityhash/city.cpp
+++ b/ext/cityhash/city.cpp
@@ -53,13 +53,39 @@ static uint32 UNALIGNED_LOAD32(const char *p) {
 #ifdef _MSC_VER
 #define bswap_32(x) _byteswap_ulong(x)
 #define bswap_64(x) _byteswap_uint64(x)
+
 #elif defined(__GLIBC__)
 #include <byteswap.h>
+
 #elif defined(__APPLE__)
 // Mac OS X / Darwin features
 #include <libkern/OSByteOrder.h>
 #define bswap_32(x) OSSwapInt32(x)
 #define bswap_64(x) OSSwapInt64(x)
+
+#elif defined(__sun) || defined(sun)
+#include <sys/byteorder.h>
+#define bswap_32(x) BSWAP_32(x)
+#define bswap_64(x) BSWAP_64(x)
+
+#elif defined(__FreeBSD__)
+#include <sys/endian.h>
+#define bswap_32(x) bswap32(x)
+#define bswap_64(x) bswap64(x)
+
+#elif defined(__OpenBSD__)
+#include <sys/types.h>
+#define bswap_32(x) swap32(x)
+#define bswap_64(x) swap64(x)
+
+#elif defined(__NetBSD__)
+#include <sys/types.h>
+#include <machine/bswap.h>
+#if defined(__BSWAP_RENAME) && !defined(__bswap_32)
+#define bswap_32(x) bswap32(x)
+#define bswap_64(x) bswap64(x)
+#endif
+
 #else
 #define bswap_32(x) (0 | ((x & 0x000000ff) << 24) \
                        | ((x & 0x0000ff00) << 8)  \
@@ -105,8 +131,8 @@ static const uint64 k1 = 0xb492b66fbe98f273ULL;
 static const uint64 k2 = 0x9ae16a3b2f90404fULL;
 
 // Magic numbers for 32-bit hashing.  Copied from Murmur3.
-static const uint32_t c1 = 0xcc9e2d51;
-static const uint32_t c2 = 0x1b873593;
+static const uint32 c1 = 0xcc9e2d51;
+static const uint32 c2 = 0x1b873593;
 
 // A 32-bit to 32-bit integer hash copied from Murmur3.
 static uint32 fmix(uint32 h)
@@ -153,7 +179,8 @@ static uint32 Hash32Len0to4(const char *s, size_t len) {
   uint32 b = 0;
   uint32 c = 9;
   for (size_t i = 0; i < len; i++) {
-    b = b * c1 + s[i];
+    signed char v = s[i];
+    b = b * c1 + v;
     c ^= b;
   }
   return fmix(Mur(b, Mur(len, c)));
diff --git a/ext/cityhash/city.h b/ext/cityhash/city.h
index ec52f2b5b2..94499ce419 100644
--- a/ext/cityhash/city.h
+++ b/ext/cityhash/city.h
@@ -38,6 +38,7 @@
 // nearest competitor is Bob Jenkins' Spooky.  We don't have great data for
 // other 64-bit CPUs, but for long strings we know that Spooky is slightly
 // faster than CityHash on some relatively recent AMD x86-64 CPUs, for example.
+// Note that CityHashCrc128 is declared in citycrc.h.
 //
 // For 32-bit x86 code, we don't know of anything faster than CityHash32 that
 // is of comparable quality.  We believe our nearest competitor is Murmur3A.
@@ -45,6 +46,9 @@
 //
 // Functions in the CityHash family are not suitable for cryptography.
 //
+// Please see CityHash's README file for more details on our performance
+// measurements and so on.
+//
 // WARNING: This code has been only lightly tested on big-endian platforms!
 // It is known to work well on little-endian platforms that have a small penalty
 // for unaligned reads, such as current Intel and AMD moderate-to-high-end CPUs.