diff --git a/include/common/buffer.h b/include/common/buffer.h
index 6f5c8dd32..976085e5e 100644
--- a/include/common/buffer.h
+++ b/include/common/buffer.h
@@ -52,7 +52,7 @@ extern struct pool_head *pool_head_buffer;
 extern struct buffer buf_empty;
 extern struct buffer buf_wanted;
 extern struct list buffer_wq;
-__decl_hathreads(HA_SPINLOCK_T buffer_wq_lock);
+__decl_hathreads(extern HA_SPINLOCK_T buffer_wq_lock);
 
 int init_buffer();
 void deinit_buffer();
diff --git a/include/proto/fd.h b/include/proto/fd.h
index f81c64624..ce23c1cf2 100644
--- a/include/proto/fd.h
+++ b/include/proto/fd.h
@@ -39,9 +39,9 @@ extern int fd_cache_num;            // number of events in the cache
 extern THREAD_LOCAL int *fd_updt;  // FD updates list
 extern THREAD_LOCAL int fd_nbupdt; // number of updates in the list
 
-__decl_hathreads(HA_SPINLOCK_T fdtab_lock);      /* global lock to protect fdtab array */
-__decl_hathreads(HA_RWLOCK_T   fdcache_lock);    /* global lock to protect fd_cache array */
-__decl_hathreads(HA_SPINLOCK_T poll_lock);       /* global lock to protect poll info */
+__decl_hathreads(extern HA_SPINLOCK_T fdtab_lock);      /* global lock to protect fdtab array */
+__decl_hathreads(extern HA_RWLOCK_T   fdcache_lock);    /* global lock to protect fd_cache array */
+__decl_hathreads(extern HA_SPINLOCK_T poll_lock);       /* global lock to protect poll info */
 
 /* Deletes an FD from the fdsets, and recomputes the maxfd limit.
  * The file descriptor is also closed.