diff --git a/include/linux/string.h b/include/linux/string.h
index 7f2eb6a..ee5e9cc 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -105,6 +105,7 @@
 #endif
 
 extern char *kstrdup(const char *s, gfp_t gfp);
+extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
 extern void *kmemdup(const void *src, size_t len, gfp_t gfp);
 
 #ifdef __cplusplus