diff --git a/stdio-common/vfprintf.c b/stdio-common/vfprintf.c
index 9eb6295c5d..50b4f02580 100644
--- a/stdio-common/vfprintf.c
+++ b/stdio-common/vfprintf.c
@@ -23,6 +23,7 @@ Boston, MA 02111-1307, USA.  */
 #include <stdlib.h>
 #include <errno.h>
 #include <wchar.h>
+#include <libc-lock.h>
 #include "_itoa.h"
 #include "../locale/localeinfo.h"