diff --git a/cdatapack/cdatapack_get.c b/cdatapack/cdatapack_get.c
--- a/cdatapack/cdatapack_get.c
+++ b/cdatapack/cdatapack_get.c
@@ -6,11 +6,12 @@
 
 #include <inttypes.h>
 #include <memory.h>
+#include <sha1dc/sha1.h>
 #include <stdio.h>
+#include <stdlib.h>
+
 #include "convert.h"
-#include "sha1/sha1.h"
 #include "cdatapack.h"
-#include <stdlib.h>
 
 #define DATAIDX_EXT  ".dataidx"
 #define DATAPACK_EXT ".datapack"
diff --git a/cfastmanifest/checksum.c b/cfastmanifest/checksum.c
--- a/cfastmanifest/checksum.c
+++ b/cfastmanifest/checksum.c
@@ -5,7 +5,7 @@
 //
 // no-check-code
 
-#include "sha1/sha1.h"
+#include <sha1dc/sha1.h>
 
 #include "node.h"
 #include "tree.h"
diff --git a/ctreemanifest/manifest.cpp b/ctreemanifest/manifest.cpp
--- a/ctreemanifest/manifest.cpp
+++ b/ctreemanifest/manifest.cpp
@@ -7,7 +7,7 @@
 //
 // no-check-code
 
-#include "sha1/sha1.h"
+#include <sha1dc/sha1.h>
 
 #include "manifest.h"
 
diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -160,16 +160,19 @@
         'datapack': {
             "sources" : ["cdatapack/cdatapack.c"],
             "include_dirs" : ["clib"] + include_dirs,
-            "libraries" : ["lz4", "sha1"],
+            "libraries" : ["lz4", "sha1detectcoll"],
             "extra_args" : filter(None,
                 [STDC99, WALL, WERROR, WSTRICTPROTOTYPES] + cflags),
         },
         'mpatch': {
             'sources': ['cstore/mpatch.c']
         },
-        "sha1": {
-            "sources" : ["clib/sha1/sha1.c", "clib/sha1/ubc_check.c"],
-            "include_dirs" : ["clib/sha1"] + include_dirs,
+        "sha1detectcoll": {
+            "sources" : [
+                "third-party/sha1dc/sha1.c",
+                "third-party/sha1dc/ubc_check.c",
+            ],
+            "include_dirs" : ["third-party"] + include_dirs,
             "extra_args" : filter(None,
                 [STDC99, WALL, WERROR, WSTRICTPROTOTYPES] + cflags),
         },
@@ -246,6 +249,7 @@
                     'cdatapack',
                     'clib',
                     'cstore',
+                    'third-party',
                 ] + include_dirs,
                 library_dirs=[
                     'build/' + distutils_dir_name('lib'),
@@ -254,7 +258,7 @@
                     'datapack',
                     'lz4',
                     'mpatch',
-                    'sha1',
+                    'sha1detectcoll',
                 ],
                 extra_compile_args=filter(None, [STDCPP0X, WALL] + cflags),
             ),
@@ -278,9 +282,10 @@
                 include_dirs=[
                     'cfastmanifest',
                     'clib',
+                    'third-party',
                 ] + include_dirs,
                 library_dirs=library_dirs,
-                libraries=['sha1'],
+                libraries=['sha1detectcoll'],
                 extra_compile_args=filter(None, [
                     STDC99,
                     WALL,
diff --git a/tests/test-check-code-hg.t b/tests/test-check-code-hg.t
--- a/tests/test-check-code-hg.t
+++ b/tests/test-check-code-hg.t
@@ -8,7 +8,7 @@
 (The writing "no-che?k-code" is for not skipping this file when checking.)
 
   $ hg files "set:grep('Generated by Cython')" > $TESTTMP/cython-generated
-  $ echo "${LINTFILES:-`hg locate`}" | sed 's-\\-/-g' | grep -v clib/sha1/ > "$TESTTMP/check-files"
+  $ echo "${LINTFILES:-`hg locate`}" | sed 's-\\-/-g' | grep -v ^third-party/ > "$TESTTMP/check-files"
   $ cat "$TESTTMP/cython-generated" | while read i; do
   >     grep -F -v "$i" "$TESTTMP/check-files" > "$TESTTMP/check-files-new"
   >     mv "$TESTTMP/check-files-new" "$TESTTMP/check-files"
diff --git a/clib/sha1/LICENSE.txt b/third-party/sha1dc/LICENSE.txt
rename from clib/sha1/LICENSE.txt
rename to third-party/sha1dc/LICENSE.txt
diff --git a/clib/sha1/sha1.h b/third-party/sha1dc/sha1.h
rename from clib/sha1/sha1.h
rename to third-party/sha1dc/sha1.h
diff --git a/clib/sha1/sha1.c b/third-party/sha1dc/sha1.c
rename from clib/sha1/sha1.c
rename to third-party/sha1dc/sha1.c
diff --git a/clib/sha1/ubc_check.h b/third-party/sha1dc/ubc_check.h
rename from clib/sha1/ubc_check.h
rename to third-party/sha1dc/ubc_check.h
diff --git a/clib/sha1/ubc_check.c b/third-party/sha1dc/ubc_check.c
rename from clib/sha1/ubc_check.c
rename to third-party/sha1dc/ubc_check.c