diff --git a/drivers/firmware/efi/libstub/skip_spaces.c b/drivers/firmware/efi/libstub/skip_spaces.c
index a700b3c7f7d0..159fb4e456c6 100644
--- a/drivers/firmware/efi/libstub/skip_spaces.c
+++ b/drivers/firmware/efi/libstub/skip_spaces.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 
 #include <linux/ctype.h>
+#include <linux/string.h>
 #include <linux/types.h>
 
 char *skip_spaces(const char *str)