diff --git a/src/cfunc_pointer.c b/src/cfunc_pointer.c
index 12ca494..759c390 100644
--- a/src/cfunc_pointer.c
+++ b/src/cfunc_pointer.c
@@ -199,16 +199,11 @@ mrb_value
 cfunc_pointer_to_s(mrb_state *mrb, mrb_value self)
 {
     struct cfunc_type_data *data = DATA_PTR(self);
-    size_t len;
     mrb_value str;
-    struct RString *s;
+
     const char* p = (const char*)get_cfunc_pointer_data(data);
-        
-    len = strlen(p);
-    str = mrb_str_new(mrb, 0, len);
-    s = mrb_str_ptr(str);
-    strcpy(s->ptr, p);
-    s->len = strlen(s->ptr);
+
+    str = mrb_str_new_cstr(mrb, p);
     return str;
 }
 
@@ -252,8 +247,15 @@ cfunc_pointer_addr(mrb_state *mrb, mrb_value self)
 static mrb_value
 cfunc_string_addr(mrb_state *mrb, mrb_value self)
 {
-    mrb_value ptr = cfunc_pointer_new_with_pointer(mrb, &RSTRING_PTR(self), false);
-    mrb_obj_iv_set(mrb, mrb_obj_ptr(ptr), mrb_intern_cstr(mrb, "parent_pointer"), self); // keep for GC
+     mrb_value ptr;
+
+     if (RSTRING(self)->flags & MRB_STR_EMBED) {
+	  const char* p = RSTRING(self)->as.ary;
+	  ptr = cfunc_pointer_new_with_pointer(mrb, &p, false);
+     } else {
+	  ptr = cfunc_pointer_new_with_pointer(mrb, &(RSTRING(self)->as.heap.ptr), false);
+     }
+     mrb_obj_iv_set(mrb, mrb_obj_ptr(ptr), mrb_intern_cstr(mrb, "parent_pointer"), self); // keep for GC
     return ptr;
 }
 
diff --git a/src/cfunc_rubyvm.c b/src/cfunc_rubyvm.c
index eedd6a6..7a18b84 100644
--- a/src/cfunc_rubyvm.c
+++ b/src/cfunc_rubyvm.c
@@ -79,7 +79,7 @@ struct task_arg* mrb_value_to_task_arg(mrb_state *mrb, mrb_value v)
 
     case MRB_TT_SYMBOL:
         {
-            size_t len;
+            mrb_int len;
             const char* name = mrb_sym2name_len(mrb, v.value.sym, &len);
             arg->value.string.len = len;
             arg->value.string.ptr = mrb_malloc(mrb, len + 1);
@@ -89,10 +89,9 @@ struct task_arg* mrb_value_to_task_arg(mrb_state *mrb, mrb_value v)
 
     case MRB_TT_STRING:
         {
-            struct RString *str = mrb_str_ptr(v);
-            arg->value.string.len = str->len;
+            arg->value.string.len = RSTRING_LEN(v);
             arg->value.string.ptr = mrb_malloc(mrb, arg->value.string.len+1);
-            memcpy(arg->value.string.ptr, str->ptr, arg->value.string.len+1);
+            memcpy(arg->value.string.ptr, RSTRING_PTR(v), arg->value.string.len+1);
         }
         break;