diff --git a/include/linux/string.h b/include/linux/string.h
index a716ee2..a176db2 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -123,6 +123,7 @@
 extern void argv_free(char **argv);
 
 extern bool sysfs_streq(const char *s1, const char *s2);
+extern int strtobool(const char *s, bool *res);
 
 #ifdef CONFIG_BINARY_PRINTF
 int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args);