diff --git a/mes.c b/mes.c
index 808a64e7..7e5ba3a5 100644
--- a/mes.c
+++ b/mes.c
@@ -184,6 +184,7 @@ SCM r3 = 0; // param 3
 #define MAKE_CHAR(n) make_cell (tmp_num_ (CHAR), 0, tmp_num2_ (n))
 #define MAKE_NUMBER(n) make_cell (tmp_num_ (NUMBER), 0, tmp_num2_ (n))
 #define MAKE_REF(n) make_cell (tmp_num_ (REF), n, 0);
+#define MAKE_STRING(x) make_cell (tmp_num_ (STRING), x, 0);
 
 SCM display_ (FILE* f, SCM x);
 SCM vm_call (function0_t f, SCM p1, SCM p2, SCM a);
@@ -693,13 +694,6 @@ tmp_num2_ (int x)
   return tmp_num2;
 }
 
-SCM
-make_string (SCM x)
-{
-  g_cells[tmp_num].value = STRING;
-  return make_cell (tmp_num, x, 0);
-}
-
 SCM
 cstring_to_list (char const* s)
 {
diff --git a/string.c b/string.c
index f3eb2b17..1bc16298 100644
--- a/string.c
+++ b/string.c
@@ -21,7 +21,7 @@
 SCM
 string (SCM x) ///((arity . n))
 {
-  return make_string (x);
+  return MAKE_STRING (x);
 }
 
 SCM
@@ -35,13 +35,13 @@ string_append (SCM x) ///((arity . n))
       p = append2 (p, STRING (s));
       x = cdr (x);
     }
-  return make_string (p);
+  return MAKE_STRING (p);
 }
 
 SCM
 list_to_string (SCM x)
 {
-  return make_string (x);
+  return MAKE_STRING (x);
 }
 
 SCM
@@ -81,7 +81,7 @@ substring (SCM x) ///((arity . n))
     p = append2 (p, cons (MAKE_CHAR (VALUE (car (s))), cell_nil));
     s = cdr (s);
   }
-  return make_string (p);
+  return MAKE_STRING (p);
 }
 
 SCM
@@ -94,7 +94,7 @@ number_to_string (SCM x)
     p = cons (MAKE_CHAR (n % 10 + '0'), p);
     n = n / 10;
   } while (n);
-  return make_string (p);
+  return MAKE_STRING (p);
 }
 
 SCM
@@ -108,7 +108,7 @@ SCM
 symbol_to_string (SCM x)
 {
   assert (TYPE (x) == SYMBOL);
-  return make_string (STRING (x));
+  return MAKE_STRING (STRING (x));
 }
 
 SCM