diff --git a/doc/chibi-scheme.1 b/doc/chibi-scheme.1
index ce148dca..505f08b0 100644
--- a/doc/chibi-scheme.1
+++ b/doc/chibi-scheme.1
@@ -89,6 +89,9 @@ and primitives coded in C.
 .BI -r
 Run the "main" procedure when the script finishes loading as in SRFI-22.
 .TP
+.BI -s
+Strict mode, escalating warnings to fatal errors.
+.TP
 .BI -f
 Change the reader to case-fold symbols as in R5RS.
 .TP
diff --git a/eval.c b/eval.c
index 1c8e8118..3ad188de 100644
--- a/eval.c
+++ b/eval.c
@@ -35,6 +35,7 @@ sexp sexp_compile_error (sexp ctx, const char *message, sexp o) {
 
 void sexp_warn (sexp ctx, char *msg, sexp x) {
   sexp_gc_var1(out);
+  int strictp = sexp_truep(sexp_global(ctx, SEXP_G_STRICT_P));
   sexp_gc_preserve1(ctx, out);
   out = sexp_current_error_port(ctx);
   if (sexp_not(out)) {          /* generate a throw-away port */
@@ -42,12 +43,14 @@ void sexp_warn (sexp ctx, char *msg, sexp x) {
     sexp_port_no_closep(out) = 1;
   }
   if (sexp_oportp(out)) {
-    sexp_write_string(ctx, "WARNING: ", out);
+    sexp_write_string(ctx, strictp ? "ERROR: " : "WARNING: ", out);
     sexp_write_string(ctx, msg, out);
     sexp_write(ctx, x, out);
     sexp_write_char(ctx, '\n', out);
+    if (strictp) sexp_stack_trace(ctx, out);
   }
   sexp_gc_release1(ctx);
+  if (strictp) exit(1);
 }
 
 sexp sexp_warn_undefs_op (sexp ctx, sexp self, sexp_sint_t n, sexp from, sexp to, sexp res) {
diff --git a/include/chibi/sexp.h b/include/chibi/sexp.h
index 4df3de3d..a49326be 100755
--- a/include/chibi/sexp.h
+++ b/include/chibi/sexp.h
@@ -1201,6 +1201,7 @@ enum sexp_context_globals {
   SEXP_G_ERR_HANDLER,
   SEXP_G_RESUMECC_BYTECODE,
   SEXP_G_FINAL_RESUMER,
+  SEXP_G_STRICT_P,
 #if SEXP_USE_FOLD_CASE_SYMS
   SEXP_G_FOLD_CASE_P,
 #endif
diff --git a/main.c b/main.c
index 915e094a..4e4c194f 100644
--- a/main.c
+++ b/main.c
@@ -448,12 +448,16 @@ void run_main (int argc, char **argv) {
 #if SEXP_USE_FOLD_CASE_SYMS
     case 'f':
       fold_case = 1;
-      if (ctx) sexp_global(ctx, SEXP_G_FOLD_CASE_P) = SEXP_TRUE;
+      init_context();
+      sexp_global(ctx, SEXP_G_FOLD_CASE_P) = SEXP_TRUE;
       break;
 #endif
     case 'r':
       main_symbol = argv[i][2] == '\0' ? "main" : argv[i]+2;
       break;
+    case 's':
+      init_context(); sexp_global(ctx, SEXP_G_STRICT_P) = SEXP_TRUE;
+      break;
     default:
       fprintf(stderr, "unknown option: %s\n", argv[i]);
       sexp_usage(1);
@@ -490,7 +494,7 @@ void run_main (int argc, char **argv) {
       /* load the script */
       sexp_context_tracep(ctx) = 1;
       tmp = sexp_env_bindings(env);
-#if SEXP_USE_MODULES
+#if 0 /* SEXP_USE_MODULES */
       /* use scheme load if possible for better stack traces */
       sym = sexp_intern(ctx, "load", -1);
       tmp = sexp_env_ref(sexp_global(ctx, SEXP_G_META_ENV), sym, SEXP_FALSE);
diff --git a/sexp.c b/sexp.c
index 7e1ddd5e..a79462b0 100644
--- a/sexp.c
+++ b/sexp.c
@@ -376,6 +376,7 @@ void sexp_init_context_globals (sexp ctx) {
 #if ! SEXP_USE_GLOBAL_SYMBOLS
   sexp_global(ctx, SEXP_G_SYMBOLS) = sexp_make_vector(ctx, sexp_make_fixnum(SEXP_SYMBOL_TABLE_SIZE), SEXP_NULL);
 #endif
+  sexp_global(ctx, SEXP_G_STRICT_P) = SEXP_FALSE;
 #if SEXP_USE_FOLD_CASE_SYMS
   sexp_global(ctx, SEXP_G_FOLD_CASE_P) = sexp_make_boolean(SEXP_DEFAULT_FOLD_CASE_SYMS);
 #endif