diff --git a/cbits/HsMsync.h b/cbits/HsMsync.h
new file mode 100644
--- /dev/null
+++ b/cbits/HsMsync.h
@@ -0,0 +1,8 @@
+#ifndef __HSMSYNC_H_
+#define __HSMSYNC_H_
+
+#include <stdlib.h>
+
+int system_io_msync(void *, size_t, int hs_flags);
+
+#endif
diff --git a/keyvaluehash.cabal b/keyvaluehash.cabal
--- a/keyvaluehash.cabal
+++ b/keyvaluehash.cabal
@@ -1,5 +1,5 @@
 name:                keyvaluehash
-version:             0.3.1
+version:             0.3.1.1
 synopsis:            Pure Haskell key/value store implementation
 description:         A simple bytestring key/value store implemented
                      in terms of hash table over a file.
@@ -20,6 +20,7 @@
 category:            Database
 build-type:          Simple
 cabal-version:       >=1.8
+Extra-Source-Files:  cbits/HsMsync.h
 
 library
   hs-Source-Dirs:      src