diff --git a/lib/jhash.h b/lib/jhash.h
index 86a721c..44dd1b5 100644
--- a/lib/jhash.h
+++ b/lib/jhash.h
@@ -24,12 +24,12 @@
  * of bytes.  No alignment or length assumptions are made about
  * the input key.
  */
-u_int32_t jhash(void *key, u_int32_t length, u_int32_t initval);
+extern u_int32_t jhash(void *key, u_int32_t length, u_int32_t initval);
 
 /* A special optimized version that handles 1 or more of u_int32_ts.
  * The length parameter here is the number of u_int32_ts in the key.
  */
-u_int32_t jhash2(u_int32_t *k, u_int32_t length, u_int32_t initval);
+extern u_int32_t jhash2(u_int32_t *k, u_int32_t length, u_int32_t initval);
 
 /* A special ultra-optimized versions that knows they are hashing exactly
  * 3, 2 or 1 word(s).
@@ -37,8 +37,8 @@
  * NOTE: In partilar the "c += length; __jhash_mix(a,b,c);" normally
  *       done at the end is not done here.
  */
-u_int32_t jhash_3words(u_int32_t a, u_int32_t b, u_int32_t c, u_int32_t initval);
-u_int32_t jhash_2words(u_int32_t a, u_int32_t b, u_int32_t initval);
-u_int32_t jhash_1word(u_int32_t a, u_int32_t initval);
+extern u_int32_t jhash_3words(u_int32_t a, u_int32_t b, u_int32_t c, u_int32_t initval);
+extern u_int32_t jhash_2words(u_int32_t a, u_int32_t b, u_int32_t initval);
+extern u_int32_t jhash_1word(u_int32_t a, u_int32_t initval);
 
 #endif /* _QUAGGA_JHASH_H */