diff --git a/include/lib/libc/stdlib.h b/include/lib/libc/stdlib.h
index 3b5e915..a0354fa 100644
--- a/include/lib/libc/stdlib.h
+++ b/include/lib/libc/stdlib.h
@@ -27,4 +27,5 @@
 
 long strtol(const char *nptr, char **endptr, int base);
 unsigned long strtoul(const char *nptr, char **endptr, int base);
+long long strtoll(const char *nptr, char **endptr, int base);
 #endif /* STDLIB_H */