diff --git a/extlib/benz/blob.c b/extlib/benz/blob.c
index cd5be767..4ca4006d 100644
--- a/extlib/benz/blob.c
+++ b/extlib/benz/blob.c
@@ -203,7 +203,7 @@ pic_blob_list_to_bytevector(pic_state *pic)
 {
   pic_blob *blob;
   unsigned char *data;
-  pic_value list, e;
+  pic_value list, e, it;
 
   pic_get_args(pic, "o", &list);
 
@@ -211,7 +211,7 @@ pic_blob_list_to_bytevector(pic_state *pic)
 
   data = blob->data;
 
-  pic_for_each (e, list) {
+  pic_for_each (e, list, it) {
     pic_assert_type(pic, e, int);
 
     if (pic_int(e) < 0 || pic_int(e) > 255)
diff --git a/extlib/benz/codegen.c b/extlib/benz/codegen.c
index 51d94e6a..91e0a4f0 100644
--- a/extlib/benz/codegen.c
+++ b/extlib/benz/codegen.c
@@ -344,9 +344,9 @@ static void
 analyze_deferred(analyze_state *state)
 {
   pic_state *pic = state->pic;
-  pic_value defer, val, name, formal, body, dst;
+  pic_value defer, val, name, formal, body, dst, it;
 
-  pic_for_each (defer, pic_reverse(pic, state->scope->defer)) {
+  pic_for_each (defer, pic_reverse(pic, state->scope->defer), it) {
     name = pic_list_ref(pic, defer, 0);
     formal = pic_list_ref(pic, defer, 1);
     body = pic_list_ref(pic, defer, 2);
@@ -566,7 +566,7 @@ analyze_quote(analyze_state *state, pic_value obj)
 
 #define FOLD_ARGS(sym) do {                             \
     obj = analyze(state, pic_car(pic, args), false);    \
-    pic_for_each (arg, pic_cdr(pic, args)) {            \
+    pic_for_each (arg, pic_cdr(pic, args), it) {        \
       obj = pic_list3(pic, pic_obj_value(sym), obj,     \
                       analyze(state, arg, false));      \
     }                                                   \
@@ -576,7 +576,7 @@ static pic_value
 analyze_add(analyze_state *state, pic_value obj, bool tailpos)
 {
   pic_state *pic = state->pic;
-  pic_value args, arg;
+  pic_value args, arg, it;
 
   ARGC_ASSERT_GE(0);
   switch (pic_length(pic, obj)) {
@@ -595,7 +595,7 @@ static pic_value
 analyze_sub(analyze_state *state, pic_value obj)
 {
   pic_state *pic = state->pic;
-  pic_value args, arg;
+  pic_value args, arg, it;
 
   ARGC_ASSERT_GE(1);
   switch (pic_length(pic, obj)) {
@@ -613,7 +613,7 @@ static pic_value
 analyze_mul(analyze_state *state, pic_value obj, bool tailpos)
 {
   pic_state *pic = state->pic;
-  pic_value args, arg;
+  pic_value args, arg, it;
 
   ARGC_ASSERT_GE(0);
   switch (pic_length(pic, obj)) {
@@ -632,7 +632,7 @@ static pic_value
 analyze_div(analyze_state *state, pic_value obj)
 {
   pic_state *pic = state->pic;
-  pic_value args, arg;
+  pic_value args, arg, it;
 
   ARGC_ASSERT_GE(1);
   switch (pic_length(pic, obj)) {
@@ -651,7 +651,7 @@ static pic_value
 analyze_call(analyze_state *state, pic_value obj, bool tailpos)
 {
   pic_state *pic = state->pic;
-  pic_value seq, elt;
+  pic_value seq, elt, it;
   pic_sym *call;
 
   if (! tailpos) {
@@ -660,7 +660,7 @@ analyze_call(analyze_state *state, pic_value obj, bool tailpos)
     call = pic->sTAILCALL;
   }
   seq = pic_list1(pic, pic_obj_value(call));
-  pic_for_each (elt, obj) {
+  pic_for_each (elt, obj, it) {
     seq = pic_cons(pic, analyze(state, elt, false), seq);
   }
   return pic_reverse(pic, seq);
@@ -670,14 +670,14 @@ static pic_value
 analyze_values(analyze_state *state, pic_value obj, bool tailpos)
 {
   pic_state *pic = state->pic;
-  pic_value v, seq;
+  pic_value v, seq, it;
 
   if (! tailpos) {
     return analyze_call(state, obj, false);
   }
 
   seq = pic_list1(pic, pic_obj_value(pic->sRETURN));
-  pic_for_each (v, pic_cdr(pic, obj)) {
+  pic_for_each (v, pic_cdr(pic, obj), it) {
     seq = pic_cons(pic, analyze(state, v, false), seq);
   }
   return pic_reverse(pic, seq);
@@ -964,7 +964,7 @@ push_codegen_context(codegen_state *state, pic_value name, pic_value args, pic_v
 {
   pic_state *pic = state->pic;
   codegen_context *cxt;
-  pic_value var;
+  pic_value var, it;
   pic_sym *sym;
 
   assert(pic_sym_p(name) || pic_false_p(name));
@@ -980,15 +980,15 @@ push_codegen_context(codegen_state *state, pic_value name, pic_value args, pic_v
   xv_init(&cxt->locals, sizeof(pic_sym *));
   xv_init(&cxt->captures, sizeof(pic_sym *));
 
-  pic_for_each (var, args) {
+  pic_for_each (var, args, it) {
     sym = pic_sym_ptr(var);
     xv_push(&cxt->args, &sym);
   }
-  pic_for_each (var, locals) {
+  pic_for_each (var, locals, it) {
     sym = pic_sym_ptr(var);
     xv_push(&cxt->locals, &sym);
   }
-  pic_for_each (var, captures) {
+  pic_for_each (var, captures, it) {
     sym = pic_sym_ptr(var);
     xv_push(&cxt->captures, &sym);
   }
@@ -1240,10 +1240,10 @@ codegen(codegen_state *state, pic_value obj)
     return;
   }
   else if (sym == pic->sBEGIN) {
-    pic_value elt;
+    pic_value elt, it;
     int i = 0;
 
-    pic_for_each (elt, pic_cdr(pic, obj)) {
+    pic_for_each (elt, pic_cdr(pic, obj), it) {
       if (i++ != 0) {
         cxt->code[cxt->clen].insn = OP_POP;
         cxt->clen++;
@@ -1406,9 +1406,9 @@ codegen(codegen_state *state, pic_value obj)
   }
   else if (sym == pic->sCALL || sym == pic->sTAILCALL) {
     int len = (int)pic_length(pic, obj);
-    pic_value elt;
+    pic_value elt, it;
 
-    pic_for_each (elt, pic_cdr(pic, obj)) {
+    pic_for_each (elt, pic_cdr(pic, obj), it) {
       codegen(state, elt);
     }
     cxt->code[cxt->clen].insn = (sym == pic->sCALL) ? OP_CALL : OP_TAILCALL;
@@ -1432,9 +1432,9 @@ codegen(codegen_state *state, pic_value obj)
   }
   else if (sym == pic->sRETURN) {
     int len = (int)pic_length(pic, obj);
-    pic_value elt;
+    pic_value elt, it;
 
-    pic_for_each (elt, pic_cdr(pic, obj)) {
+    pic_for_each (elt, pic_cdr(pic, obj), it) {
       codegen(state, elt);
     }
     cxt->code[cxt->clen].insn = OP_RET;
diff --git a/extlib/benz/cont.c b/extlib/benz/cont.c
index 2678fb0b..17587e95 100644
--- a/extlib/benz/cont.c
+++ b/extlib/benz/cont.c
@@ -195,11 +195,11 @@ pic_values_by_array(pic_state *pic, size_t argc, pic_value *argv)
 pic_value
 pic_values_by_list(pic_state *pic, pic_value list)
 {
-  pic_value v;
+  pic_value v, it;
   int i;
 
   i = 0;
-  pic_for_each (v, list) {
+  pic_for_each (v, list, it) {
     pic->sp[i++] = v;
   }
   pic->ci->retc = i;
diff --git a/extlib/benz/dict.c b/extlib/benz/dict.c
index d677e935..4312c40f 100644
--- a/extlib/benz/dict.c
+++ b/extlib/benz/dict.c
@@ -273,13 +273,13 @@ static pic_value
 pic_dict_alist_to_dictionary(pic_state *pic)
 {
   struct pic_dict *dict;
-  pic_value alist, e;
+  pic_value alist, e, it;
 
   pic_get_args(pic, "o", &alist);
 
   dict = pic_make_dict(pic);
 
-  pic_for_each (e, pic_reverse(pic, alist)) {
+  pic_for_each (e, pic_reverse(pic, alist), it) {
     pic_assert_type(pic, pic_car(pic, e), sym);
     pic_dict_set(pic, dict, pic_sym_ptr(pic_car(pic, e)), pic_cdr(pic, e));
   }
diff --git a/extlib/benz/include/picrin/pair.h b/extlib/benz/include/picrin/pair.h
index 11859482..3b3e29b0 100644
--- a/extlib/benz/include/picrin/pair.h
+++ b/extlib/benz/include/picrin/pair.h
@@ -59,12 +59,9 @@ pic_value pic_list7(pic_state *, pic_value, pic_value, pic_value, pic_value, pic
 pic_value pic_list_by_array(pic_state *, size_t, pic_value *);
 pic_value pic_make_list(pic_state *, size_t, pic_value);
 
-#define pic_for_each(var, list)                         \
-  pic_for_each_helper_(var, PIC_GENSYM(tmp), list)
-#define pic_for_each_helper_(var, tmp, list)                            \
-  for (pic_value tmp = (list);                                          \
-       pic_nil_p(tmp) ? false : ((var = pic_car(pic, tmp)), true);      \
-       tmp = pic_cdr(pic, tmp))
+#define pic_for_each(var, list, it)                             \
+  for (it = (list); ! pic_nil_p(it); it = pic_cdr(pic, it))     \
+    if ((var = pic_car(pic, it)), true)
 
 #define pic_push(pic, item, place) (place = pic_cons(pic, item, place))
 #define pic_pop(pic, place) (place = pic_cdr(pic, place))
diff --git a/extlib/benz/lib.c b/extlib/benz/lib.c
index 234f3833..0c4ad001 100644
--- a/extlib/benz/lib.c
+++ b/extlib/benz/lib.c
@@ -73,7 +73,7 @@ import_table(pic_state *pic, pic_value spec, struct pic_dict *imports)
 {
   struct pic_lib *lib;
   struct pic_dict *table;
-  pic_value val, tmp, prefix;
+  pic_value val, tmp, prefix, it;
   pic_sym *sym, *id, *tag;
 
   table = pic_make_dict(pic);
@@ -85,7 +85,7 @@ import_table(pic_state *pic, pic_value spec, struct pic_dict *imports)
     if (tag == pic->sONLY) {
       import_table(pic, pic_cadr(pic, spec), table);
 
-      pic_for_each (val, pic_cddr(pic, spec)) {
+      pic_for_each (val, pic_cddr(pic, spec), it) {
         pic_dict_set(pic, imports, pic_sym_ptr(val), pic_dict_ref(pic, table, pic_sym_ptr(val)));
       }
       return;
@@ -93,7 +93,7 @@ import_table(pic_state *pic, pic_value spec, struct pic_dict *imports)
     if (tag == pic->sRENAME) {
       import_table(pic, pic_cadr(pic, spec), imports);
 
-      pic_for_each (val, pic_cddr(pic, spec)) {
+      pic_for_each (val, pic_cddr(pic, spec), it) {
         tmp = pic_dict_ref(pic, imports, pic_sym_ptr(pic_car(pic, val)));
         pic_dict_del(pic, imports, pic_sym_ptr(pic_car(pic, val)));
         pic_dict_set(pic, imports, pic_sym_ptr(pic_cadr(pic, val)), tmp);
@@ -112,7 +112,7 @@ import_table(pic_state *pic, pic_value spec, struct pic_dict *imports)
     }
     if (tag == pic->sEXCEPT) {
       import_table(pic, pic_cadr(pic, spec), imports);
-      pic_for_each (val, pic_cddr(pic, spec)) {
+      pic_for_each (val, pic_cddr(pic, spec), it) {
         pic_dict_del(pic, imports, pic_sym_ptr(val));
       }
       return;
@@ -202,13 +202,13 @@ static bool
 condexpand(pic_state *pic, pic_value clause)
 {
   pic_sym *tag;
-  pic_value c, feature;
+  pic_value c, feature, it;
 
   if (pic_eq_p(clause, pic_obj_value(pic->sELSE))) {
     return true;
   }
   if (pic_sym_p(clause)) {
-    pic_for_each (feature, pic->features) {
+    pic_for_each (feature, pic->features, it) {
       if(pic_eq_p(feature, clause))
         return true;
     }
@@ -228,14 +228,14 @@ condexpand(pic_state *pic, pic_value clause)
     return ! condexpand(pic, pic_list_ref(pic, clause, 1));
   }
   if (tag == pic->sAND) {
-    pic_for_each (c, pic_cdr(pic, clause)) {
+    pic_for_each (c, pic_cdr(pic, clause), it) {
       if (! condexpand(pic, c))
         return false;
     }
     return true;
   }
   if (tag == pic->sOR) {
-    pic_for_each (c, pic_cdr(pic, clause)) {
+    pic_for_each (c, pic_cdr(pic, clause), it) {
       if (condexpand(pic, c))
         return true;
     }
diff --git a/extlib/benz/macro.c b/extlib/benz/macro.c
index 622a28d3..f934cdd3 100644
--- a/extlib/benz/macro.c
+++ b/extlib/benz/macro.c
@@ -124,9 +124,9 @@ macroexpand_defer(pic_state *pic, pic_value expr, struct pic_senv *senv)
 static void
 macroexpand_deferred(pic_state *pic, struct pic_senv *senv)
 {
-  pic_value defer, val, src, dst;
+  pic_value defer, val, src, dst, it;
 
-  pic_for_each (defer, pic_reverse(pic, senv->defer)) {
+  pic_for_each (defer, pic_reverse(pic, senv->defer), it) {
     src = pic_car(pic, defer);
     dst = pic_cdr(pic, defer);
 
diff --git a/extlib/benz/pair.c b/extlib/benz/pair.c
index 03621ec1..fc865921 100644
--- a/extlib/benz/pair.c
+++ b/extlib/benz/pair.c
@@ -204,10 +204,10 @@ pic_value
 pic_reverse(pic_state *pic, pic_value list)
 {
   size_t ai = pic_gc_arena_preserve(pic);
-  pic_value v, acc;
+  pic_value v, acc, it;
 
   acc = pic_nil_value();
-  pic_for_each(v, list) {
+  pic_for_each(v, list, it) {
     acc = pic_cons(pic, v, acc);
 
     pic_gc_arena_restore(pic, ai);
@@ -220,10 +220,10 @@ pic_value
 pic_append(pic_state *pic, pic_value xs, pic_value ys)
 {
   size_t ai = pic_gc_arena_preserve(pic);
-  pic_value x;
+  pic_value x, it;
 
   xs = pic_reverse(pic, xs);
-  pic_for_each (x, xs) {
+  pic_for_each (x, xs, it) {
     ys = pic_cons(pic, x, ys);
 
     pic_gc_arena_restore(pic, ai);
diff --git a/extlib/benz/string.c b/extlib/benz/string.c
index 43514b2d..abdefad0 100644
--- a/extlib/benz/string.c
+++ b/extlib/benz/string.c
@@ -425,7 +425,7 @@ static pic_value
 pic_str_list_to_string(pic_state *pic)
 {
   pic_str *str;
-  pic_value list, e;
+  pic_value list, e, it;
   size_t i = 0;
 
   pic_get_args(pic, "o", &list);
@@ -435,7 +435,7 @@ pic_str_list_to_string(pic_state *pic)
   } else {
     char buf[pic_length(pic, list)];
 
-    pic_for_each (e, list) {
+    pic_for_each (e, list, it) {
       pic_assert_type(pic, e, char);
 
       buf[i++] = pic_char(e);
diff --git a/extlib/benz/vector.c b/extlib/benz/vector.c
index 33070d24..60004cc8 100644
--- a/extlib/benz/vector.c
+++ b/extlib/benz/vector.c
@@ -302,7 +302,7 @@ static pic_value
 pic_vec_list_to_vector(pic_state *pic)
 {
   struct pic_vector *vec;
-  pic_value list, e, *data;
+  pic_value list, e, it, *data;
 
   pic_get_args(pic, "o", &list);
 
@@ -310,7 +310,7 @@ pic_vec_list_to_vector(pic_state *pic)
 
   data = vec->data;
 
-  pic_for_each (e, list) {
+  pic_for_each (e, list, it) {
     *data++ = e;
   }
   return pic_obj_value(vec);
diff --git a/extlib/benz/vm.c b/extlib/benz/vm.c
index 0c82bdff..12862f9f 100644
--- a/extlib/benz/vm.c
+++ b/extlib/benz/vm.c
@@ -1153,13 +1153,13 @@ pic_apply_trampoline(pic_state *pic, struct pic_proc *proc, pic_value args)
     { OP_TAILCALL, { .i = -1 } }
   };
 
-  pic_value v, *sp;
+  pic_value v, it, *sp;
   pic_callinfo *ci;
 
   *pic->sp++ = pic_obj_value(proc);
 
   sp = pic->sp;
-  pic_for_each (v, args) {
+  pic_for_each (v, args, it) {
     *sp++ = v;
   }
 
diff --git a/src/main.c b/src/main.c
index 03431ac4..f43419f1 100644
--- a/src/main.c
+++ b/src/main.c
@@ -20,11 +20,11 @@ pic_features(pic_state *pic)
 static pic_value
 pic_libraries(pic_state *pic)
 {
-  pic_value libs = pic_nil_value(), lib;
+  pic_value libs = pic_nil_value(), lib, it;
 
   pic_get_args(pic, "");
 
-  pic_for_each (lib, pic->libs) {
+  pic_for_each (lib, pic->libs, it) {
     libs = pic_cons(pic, pic_car(pic, lib), libs);
   }