diff --git a/coreutils/sync.c b/coreutils/sync.c
index e7aa44585..572d74924 100644
--- a/coreutils/sync.c
+++ b/coreutils/sync.c
@@ -1,4 +1,5 @@
 #include "internal.h"
+#include <stdio.h>
 
 extern int
 sync_main(int argc, char * * argv)
diff --git a/sync.c b/sync.c
index e7aa44585..572d74924 100644
--- a/sync.c
+++ b/sync.c
@@ -1,4 +1,5 @@
 #include "internal.h"
+#include <stdio.h>
 
 extern int
 sync_main(int argc, char * * argv)