diff --git a/include/lib/libc/stdlib.h b/include/lib/libc/stdlib.h
index b4a14e8..3b5e915 100644
--- a/include/lib/libc/stdlib.h
+++ b/include/lib/libc/stdlib.h
@@ -26,4 +26,5 @@
 extern void exit(int status);
 
 long strtol(const char *nptr, char **endptr, int base);
+unsigned long strtoul(const char *nptr, char **endptr, int base);
 #endif /* STDLIB_H */