diff --git a/Makefile b/Makefile
index 7015597b..8b85794c 100644
--- a/Makefile
+++ b/Makefile
@@ -62,10 +62,10 @@ endif
 
 ifeq ($(USE_DL),0)
 XLDFLAGS  := $(LDFLAGS) $(GCLDFLAGS) -lm
-XCFLAGS   := -Wall -DUSE_DL=0 -g3 -O2 $(CFLAGS)
+XCFLAGS   := -Wall -DUSE_DL=0 -g3 $(CFLAGS)
 else
 XLDFLAGS  := $(LDFLAGS) $(GCLDFLAGS) -ldl -lm
-XCFLAGS   := -Wall -g3 -O2 $(CFLAGS)
+XCFLAGS   := -Wall -g3 $(CFLAGS)
 endif
 
 INCLUDES = include/chibi/sexp.h include/chibi/config.h include/chibi/install.h
diff --git a/config.scm b/config.scm
index 0a8f0f5c..decc94d1 100644
--- a/config.scm
+++ b/config.scm
@@ -53,7 +53,12 @@
           (let ((mod2 (load-module (cadr x))))
             (%env-copy! env (module-env mod2) (module-exports mod2))))
          ((include)
-          (for-each (lambda (f) (load (find-module-file name f) env)) (cdr x)))
+          (for-each
+           (lambda (f)
+             (cond
+              ((find-module-file name f) => (lambda (x) (load x env)))
+              (else (error "couldn't find include" f))))
+           (cdr x)))
          ((body)
           (for-each (lambda (expr) (eval expr env)) (cdr x)))))
      (module-meta-data mod))
diff --git a/eval.c b/eval.c
index 3e1a1f6e..1cff2b2f 100644
--- a/eval.c
+++ b/eval.c
@@ -2011,10 +2011,17 @@ sexp sexp_load_dl (sexp ctx, sexp file, sexp env) {
 #endif
 
 sexp sexp_load (sexp ctx, sexp source, sexp env) {
+#if USE_DL
+  char *suffix;
+#endif
   sexp tmp, out=SEXP_FALSE;
   sexp_gc_var4(ctx2, x, in, res);
+  if (! sexp_stringp(source))
+    return sexp_type_exception(ctx, "not a string", source);
+  if (! sexp_envp(env))
+    return sexp_type_exception(ctx, "not an environment", env);
 #if USE_DL
-  char *suffix = sexp_string_data(source)
+  suffix = sexp_string_data(source)
     + sexp_string_length(source) - strlen(sexp_so_extension);
   if (strcmp(suffix, sexp_so_extension) == 0) {
     res = sexp_load_dl(ctx, source, env);