diff --git a/Makefile b/Makefile
index 180e1e0..afa5d08 100644
--- a/Makefile
+++ b/Makefile
@@ -368,7 +368,7 @@ ifeq ($(uname_O),Cygwin)
 	# There are conflicting reports about this.
 	# On some boxes NO_MMAP is needed, and not so elsewhere.
 	# Try commenting this out if you suspect MMAP is more efficient
-	NO_MMAP = YesPlease
+	#NO_MMAP = YesPlease
 	NO_IPV6 = YesPlease
 	X = .exe
 endif
diff --git a/index-pack.c b/index-pack.c
index 5f6d128..f1d11a0 100644
--- a/index-pack.c
+++ b/index-pack.c
@@ -277,25 +277,27 @@ static void *get_data_from_pack(struct object_entry *obj)
 {
 	unsigned long from = obj[0].offset + obj[0].hdr_size;
 	unsigned long len = obj[1].offset - from;
-	unsigned char *src, *data;
+	unsigned pg_offset = from % getpagesize();
+	unsigned char *map, *data;
 	z_stream stream;
 	int st;
 
-	src = xmalloc(len);
-	if (pread(pack_fd, src, len, from) != len)
-		die("cannot pread pack file: %s", strerror(errno));
+	map = mmap(NULL, len + pg_offset, PROT_READ, MAP_PRIVATE,
+		   pack_fd, from - pg_offset);
+	if (map == MAP_FAILED)
+		die("cannot mmap pack file: %s", strerror(errno));
 	data = xmalloc(obj->size);
 	memset(&stream, 0, sizeof(stream));
 	stream.next_out = data;
 	stream.avail_out = obj->size;
-	stream.next_in = src;
+	stream.next_in = map + pg_offset;
 	stream.avail_in = len;
 	inflateInit(&stream);
 	while ((st = inflate(&stream, Z_FINISH)) == Z_OK);
 	inflateEnd(&stream);
 	if (st != Z_STREAM_END || stream.total_out != obj->size)
 		die("serious inflate inconsistency");
-	free(src);
+	munmap(map, len + pg_offset);
 	return data;
 }
 
diff --git a/t/t5610-clone-fail.sh b/t/t5610-clone-fail.sh
new file mode 100755
index 0000000..d46c255
--- /dev/null
+++ b/t/t5610-clone-fail.sh
@@ -0,0 +1,24 @@
+#!/bin/sh
+#
+
+test_description='test git-clone failure on cygwin using pread()
+'
+
+. ./test-lib.sh
+
+# Need a repo to clone
+test_create_repo foo2
+
+GIT_AUTHOR_EMAIL=xxxxxxxx@yyyyyyyy.yyyyy.yyyyyyy.yyy
+GIT_COMMITTER_EMAIL=xxxxxxxx@yyyyyyyy.yyyyy.yyyyyyy.yyy
+export GIT_AUTHOR_EMAIL
+export GIT_COMMITTER_EMAIL
+
+(cd foo2 && echo "Hello" > file && git add file && git commit -m 'add file' >/dev/null 2>&1)
+(cd foo2 && echo "Hello2" >> file && git commit -a -m 'test' >/dev/null 2>&1)
+
+test_expect_success \
+    'clone with resolving' \
+    'git-clone foo2 bar2'
+
+test_done