diff --git a/hash.c b/hash.c
index a0c30369fa..b5ff28ae4b 100644
--- a/hash.c
+++ b/hash.c
@@ -4,6 +4,8 @@
 #include "jenkins_hash.h"
 #include "murmur3_hash.h"
 
+hash_func hash;
+
 int hash_init(enum hashfunc_type type) {
     switch(type) {
         case JENKINS_HASH:
diff --git a/hash.h b/hash.h
index 059d1e2a67..3b2a984782 100644
--- a/hash.h
+++ b/hash.h
@@ -2,7 +2,7 @@
 #define    HASH_H
 
 typedef uint32_t (*hash_func)(const void *key, size_t length);
-hash_func hash;
+extern hash_func hash;
 
 enum hashfunc_type {
     JENKINS_HASH=0, MURMUR3_HASH