diff --git a/src/lisp/lib/std.h b/src/lisp/lib/std.h
index dae0ac3..eb129d5 100644
--- a/src/lisp/lib/std.h
+++ b/src/lisp/lib/std.h
@@ -8,5 +8,5 @@
 
 void add_function(struct environment *env, char *name, void *func, struct args *args, enum namespace ns);
 void add_c_function(struct environment *env, char *name, void *func, int nargs);
-void load_std(struct environment *env);
+struct error load_std(struct environment *env) WARN_UNUSED;
 bool load_library(struct environment *env, char *name);