diff --git a/eval.c b/eval.c
index 899e146b..e4dd8bd5 100644
--- a/eval.c
+++ b/eval.c
@@ -40,12 +40,14 @@ static void sexp_warn (sexp ctx, char *msg, sexp x) {
   }
 }
 
-void sexp_warn_undefs (sexp ctx, sexp from, sexp to, sexp res) {
+sexp sexp_warn_undefs_op (sexp ctx, sexp self, sexp_sint_t n, sexp from, sexp to, sexp res) {
   sexp x, ignore = sexp_exceptionp(res) ? sexp_exception_irritants(res) : SEXP_NULL;
+  if (sexp_envp(from)) from = sexp_env_bindings(from);
   for (x=from; sexp_pairp(x) && x!=to; x=sexp_env_next_cell(x))
     if (sexp_cdr(x) == SEXP_UNDEF && sexp_car(x) != ignore
         && sexp_not(sexp_memq(ctx, sexp_car(x), ignore)))
       sexp_warn(ctx, "reference to undefined variable: ", sexp_car(x));
+  return SEXP_VOID;
 }
 
 
@@ -1172,9 +1174,6 @@ sexp sexp_load_op (sexp ctx, sexp self, sexp_sint_t n, sexp source, sexp env) {
       res = SEXP_VOID;
     sexp_close_port(ctx, in);
   }
-#if SEXP_USE_WARN_UNDEFS
-  sexp_warn_undefs(ctx, sexp_env_bindings(env), tmp, res);
-#endif
   sexp_gc_release4(ctx);
 #if SEXP_USE_DL || SEXP_USE_STATIC_LIBS
   }
diff --git a/include/chibi/eval.h b/include/chibi/eval.h
index 14497a35..2400dcd2 100644
--- a/include/chibi/eval.h
+++ b/include/chibi/eval.h
@@ -82,7 +82,7 @@ SEXP_API sexp sexp_env_define (sexp ctx, sexp env, sexp sym, sexp val);
 SEXP_API sexp sexp_env_cell (sexp env, sexp sym, int localp);
 SEXP_API sexp sexp_env_ref (sexp env, sexp sym, sexp dflt);
 SEXP_API sexp sexp_parameter_ref (sexp ctx, sexp param);
-SEXP_API void sexp_warn_undefs (sexp ctx, sexp from, sexp to, sexp res);
+SEXP_API sexp sexp_warn_undefs_op (sexp ctx, sexp self, sexp_sint_t n, sexp from, sexp to, sexp res);
 SEXP_API sexp sexp_make_lit (sexp ctx, sexp value);
 SEXP_API sexp sexp_make_opcode (sexp, sexp, sexp, sexp, sexp, sexp, sexp, sexp, sexp, sexp, sexp, sexp, sexp_proc1);
 SEXP_API sexp sexp_make_procedure_op (sexp ctx, sexp self, sexp_sint_t n, sexp flags, sexp num_args, sexp bc, sexp vars);
@@ -145,6 +145,7 @@ SEXP_API sexp sexp_make_setter_op (sexp ctx, sexp self, sexp_sint_t n, sexp name
 #define sexp_open_input_file(ctx, x) sexp_open_input_file_op(ctx, NULL, 1, x)
 #define sexp_open_output_file(ctx, x) sexp_open_output_file_op(ctx, NULL, 1, x)
 #define sexp_close_port(ctx, x) sexp_close_port_op(ctx, NULL, 1, x)
+#define sexp_warn_undefs(ctx, from, to, res) sexp_warn_undefs_op(ctx, NULL, 3, from, to, res)
 
 #ifdef __cplusplus
 } /* extern "C" */
diff --git a/lib/meta.scm b/lib/meta.scm
index ac5cd076..a2a80f58 100644
--- a/lib/meta.scm
+++ b/lib/meta.scm
@@ -146,6 +146,7 @@
          ((body begin)
           (for-each (lambda (expr) (eval expr env)) (cdr x)))))
      (module-meta-data mod))
+    (warn-undefs env #f)
     env))
 
 (define (environment . ls)
diff --git a/main.c b/main.c
index 56a5c9c1..9c5109b9 100644
--- a/main.c
+++ b/main.c
@@ -472,7 +472,11 @@ void run_main (int argc, char **argv) {
 #endif
       /* load the script */
       sexp_context_tracep(ctx) = 1;
-      check_exception(ctx, sexp_load(ctx, tmp=sexp_c_string(ctx, argv[i], -1), env));
+      tmp = sexp_env_bindings(env);
+      check_exception(ctx, sexp_load(ctx, sym=sexp_c_string(ctx, argv[i], -1), env));
+#if SEXP_USE_WARN_UNDEFS
+      sexp_warn_undefs(ctx, env, tmp, SEXP_VOID);
+#endif
       /* SRFI-22: run main if specified */
       sym = sexp_intern(ctx, "main", -1);
       tmp = sexp_env_ref(env, sym, SEXP_FALSE);
diff --git a/opcodes.c b/opcodes.c
index 990b5bf7..0b487d3d 100644
--- a/opcodes.c
+++ b/opcodes.c
@@ -156,6 +156,7 @@ _FN2OPTP(SEXP_VOID, _I(SEXP_STRING), _I(SEXP_ENV), "load", (sexp)"interaction-en
 _FN4(SEXP_VOID, _I(SEXP_ENV), _I(SEXP_ENV), _I(SEXP_OBJECT), "%import", 0, sexp_env_import_op),
 _FN2OPTP(SEXP_VOID, _I(SEXP_EXCEPTION), _I(SEXP_OPORT), "print-exception", (sexp)"current-error-port", sexp_print_exception_op),
 _FN1OPTP(SEXP_VOID, _I(SEXP_OPORT), "print-stack-trace", (sexp)"current-error-port", sexp_stack_trace_op),
+_FN3OPT(SEXP_VOID, _I(SEXP_OBJECT), _I(SEXP_OBJECT), _I(SEXP_OBJECT), "warn-undefs", SEXP_FALSE, sexp_warn_undefs_op),
 _FN1(_I(SEXP_OBJECT), _I(SEXP_EXCEPTION), "exception-type", 0, sexp_exception_type_op),
 _FN2OPT(_I(SEXP_STRING), _I(SEXP_FIXNUM), _I(SEXP_CHAR), "make-string", sexp_make_character(' '), sexp_make_string_op),
 _FN2OPT(_I(SEXP_STRING), _I(SEXP_FIXNUM), _I(SEXP_FIXNUM), "make-bytevector", SEXP_ZERO, sexp_make_bytes_op),