diff --git a/include/common/hash.h b/include/common/hash.h
index 78fd87b..c17f8c9 100644
--- a/include/common/hash.h
+++ b/include/common/hash.h
@@ -24,10 +24,10 @@
 
 #include <inttypes.h>
 
-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);
-unsigned int hash_crc32(const char *key, int len);
-uint32_t hash_crc32c(const char *key, int len);
+unsigned int hash_djb2(const void *input, int len);
+unsigned int hash_wt6(const void *input, int len);
+unsigned int hash_sdbm(const void *input, int len);
+unsigned int hash_crc32(const void *input, int len);
+uint32_t hash_crc32c(const void *input, int len);
 
 #endif /* _COMMON_HASH_H_ */