diff --git a/unpack-trees.h b/unpack-trees.h
index c2b434c606..534358fcc5 100644
--- a/unpack-trees.h
+++ b/unpack-trees.h
@@ -82,8 +82,8 @@ struct unpack_trees_options {
 	struct exclude_list *el; /* for internal use */
 };
 
-extern int unpack_trees(unsigned n, struct tree_desc *t,
-		struct unpack_trees_options *options);
+int unpack_trees(unsigned n, struct tree_desc *t,
+		 struct unpack_trees_options *options);
 
 int verify_uptodate(const struct cache_entry *ce,
 		    struct unpack_trees_options *o);