diff --git a/btrfs-find-root.c b/btrfs-find-root.c
index 1a7a80c1..b48c8004 100644
--- a/btrfs-find-root.c
+++ b/btrfs-find-root.c
@@ -40,7 +40,7 @@ static u64 search_objectid = BTRFS_ROOT_TREE_OBJECTID;
 static u64 search_generation = 0;
 static unsigned long search_level = 0;
 
-static void usage()
+static void usage(void)
 {
 	fprintf(stderr, "Usage: find-roots [-o search_objectid] "
 		"[ -g search_generation ] [ -l search_level ] <device>\n");
diff --git a/btrfs-list.c b/btrfs-list.c
index 214cb450..55508d25 100644
--- a/btrfs-list.c
+++ b/btrfs-list.c
@@ -1418,7 +1418,7 @@ static void print_single_volume_info_default(struct root_info *subv)
 	printf("\n");
 }
 
-static void print_all_volume_info_tab_head()
+static void print_all_volume_info_tab_head(void)
 {
 	int i;
 	int len;