diff --git a/include/common/hash.h b/include/common/hash.h
index 379bf89..7039ba5 100644
--- a/include/common/hash.h
+++ b/include/common/hash.h
@@ -22,8 +22,8 @@
 #ifndef _COMMON_HASH_H_
 #define _COMMON_HASH_H_
 
-unsigned long hash_djb2(const char *key, int len);
-unsigned long hash_wt6(const char *key, int len);
-unsigned long hash_sdbm(const char *key, int len);
+unsigned int hash_djb2(const char *key, int len);
+unsigned int hash_wt6(const char *key, int len);
+unsigned int hash_sdbm(const char *key, int len);
 
 #endif /* _COMMON_HASH_H_ */