diff --git a/cbits/city.h b/cbits/city.h
--- a/cbits/city.h
+++ b/cbits/city.h
@@ -74,6 +74,11 @@
 // hashed into the result.
 uint128 CityHash128WithSeed(const char *s, size_t len, uint128 seed);
 
+uint128 CityHashCrc128(const char *s, size_t len);
+
+uint128 CityHashCrc128WithSeed(const char *s, size_t len, uint128 seed);
+
+
 // Hash 128 input bits down to 64 bits of output.
 // This is intended to be a reasonably good hash function.
 inline uint64 Hash128to64(const uint128& x) {
diff --git a/cbits/citycrc.h b/cbits/citycrc.h
new file mode 100644
--- /dev/null
+++ b/cbits/citycrc.h
@@ -0,0 +1,43 @@
+// Copyright (c) 2011 Google, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+//
+// CityHash, by Geoff Pike and Jyrki Alakuijala
+//
+// This file declares the subset of the CityHash functions that require
+// _mm_crc32_u64().  See the CityHash README for details.
+//
+// Functions in the CityHash family are not suitable for cryptography.
+
+#ifndef CITY_HASH_CRC_H_
+#define CITY_HASH_CRC_H_
+
+#include <city.h>
+
+// Hash function for a byte array.
+uint128 CityHashCrc128(const char *s, size_t len);
+
+// Hash function for a byte array.  For convenience, a 128-bit seed is also
+// hashed into the result.
+uint128 CityHashCrc128WithSeed(const char *s, size_t len, uint128 seed);
+
+// Hash function for a byte array.  Sets result[0] ... result[3].
+void CityHashCrc256(const char *s, size_t len, uint64 *result);
+
+#endif  // CITY_HASH_CRC_H_
diff --git a/cbits/hs_city.cc b/cbits/hs_city.cc
--- a/cbits/hs_city.cc
+++ b/cbits/hs_city.cc
@@ -5,17 +5,22 @@
   return CityHash64(buf,len);
 }
 
-uint64_t hs_CityHash64WithSeed(const char *buf, size_t len, uint64_t seed) {
+uint64_t hs_CityHash64WithSeed(const char* buf, size_t len, uint64_t seed) {
   return CityHash64WithSeed(buf,len,seed);
 }
 
-uint64_t hs_CityHash64WithSeeds(const char *buf, size_t len,
+uint64_t hs_CityHash64WithSeeds(const char* buf, size_t len,
                                 uint64 seed0, uint64 seed1) {
   return CityHash64WithSeeds(buf,len,seed0,seed1);
 }
 
 void hs_CityHash128(const char* buf, size_t len, uint64_t* lo, uint64_t* hi) {
+#if defined(__SSE4_2__)
+  uint128 res = CityHashCrc128(buf,len);
+#else
   uint128 res = CityHash128(buf,len);
+#endif /* defined(__SSE4_2__) */
+
   *lo = Uint128Low64(res);
   *hi = Uint128High64(res);
 }
@@ -25,7 +30,12 @@
   uint128 seed;
   seed.first = in1; seed.second = in2;
 
+#if defined(__SSE4_2__)
+  uint128 r = CityHashCrc128WithSeed(buf, len, seed);
+#else
   uint128 r = CityHash128WithSeed(buf, len, seed);
+#endif /* defined(__SSE4_2__) */
+
   *lo = Uint128Low64(r);
   *hi = Uint128High64(r);
 }
diff --git a/cityhash.cabal b/cityhash.cabal
--- a/cityhash.cabal
+++ b/cityhash.cabal
@@ -1,10 +1,14 @@
 name:                cityhash
-version:             0.2.0.0
+version:             0.3.0.0
 synopsis:            Bindings to CityHash
 description:
   This package implements a binding to the CityHash family of hashing functions (implemented in C++.)
   .
   See <http://code.google.com/p/cityhash/> for more information.
+  .
+  This package has optional SSE4.2 support. If you build it with the @-fsse42@ flag, the 128-bit
+  hashing functions will use an SSE-optimized implementation (which takes advantage of the @crc32@
+  instruction present on recent Intel/AMD machines.) The 64-bit hashing functions are unaffected.
 homepage:            http://github.com/thoughtpolice/hs-cityhash
 bug-reports:         https://github.com/thoughtpolice/hs-cityhash/issues
 license:             MIT
@@ -17,7 +21,7 @@
 tested-with:         GHC==7.0.4, GHC==7.2.1
 
 extra-source-files:
-  cbits/city.cc, cbits/city.h, cbits/config.h
+  cbits/city.cc, cbits/city.h, cbits/config.h, cbits/citycrc.h,
   cbits/hs_city.cc, cbits/hs_city.h,
   README.md, tests/Properties.hs
 
@@ -25,16 +29,21 @@
   type: git
   location: https://github.com/thoughtpolice/hs-cityhash.git
 
+flag sse42
+  default: False
+
 library
   exposed-modules: Data.Digest.CityHash
   build-depends:
-    base       >= 3 && < 5,
-    bytestring >= 0.9,
-    largeword  >= 1.0
+    base         >= 3 && < 5,
+    bytestring   >= 0.9,
+    largeword    >= 1.0
   c-sources:       cbits/city.cc, cbits/hs_city.cc
   include-dirs:    cbits
   extra-libraries: stdc++
 
+  if flag(sse42)
+    cc-options:     -D__SSE4_2__ -msse4.2
   cc-options:       -O3
   ghc-options:      -Wall -O2 -fwarn-tabs
   default-language: Haskell98