diff --git a/include/mes/mes.h b/include/mes/mes.h
index 1e94def9..ea5d7e56 100644
--- a/include/mes/mes.h
+++ b/include/mes/mes.h
@@ -81,9 +81,6 @@ SCM builtin_name (SCM builtin);
 SCM cstring_to_list (char const *s);
 SCM cstring_to_symbol (char const *s);
 SCM fdisplay_ (SCM, int, int);
-SCM gc_peek_frame ();
-SCM gc_pop_frame ();
-SCM gc_push_frame ();
 SCM init_symbols ();
 SCM init_time (SCM a);
 SCM make_builtin_type ();
@@ -119,6 +116,9 @@ void assert_max_string (size_t i, char const *msg, char *string);
 void assert_msg (int check, char *msg);
 void gc_ ();
 void gc_init ();
+void gc_peek_frame ();
+void gc_pop_frame ();
+void gc_push_frame ();
 
 #include "mes/builtins.h"
 #include "mes/constants.h"
diff --git a/src/gc.c b/src/gc.c
index 4bac1513..debf8b3d 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -440,34 +440,32 @@ gc ()
   return cell_unspecified;
 }
 
-SCM
-gc_push_frame ()                /*:((internal)) */
+void
+gc_push_frame ()
 {
-  if (g_stack < 5)
+  if (g_stack < FRAME_SIZE)
     assert_msg (0, "STACK FULL");
   g_stack_array[g_stack - 1] = cell_f;
   g_stack_array[g_stack - 2] = R0;
   g_stack_array[g_stack - 3] = R1;
   g_stack_array[g_stack - 4] = R2;
   g_stack_array[g_stack - 5] = R3;
-  g_stack = g_stack - 5;
-  return g_stack;
+  g_stack = g_stack - FRAME_SIZE;
 }
 
-SCM
-gc_peek_frame ()                /*:((internal)) */
+void
+gc_peek_frame ()
 {
   R3 = g_stack_array[g_stack];
   R2 = g_stack_array[g_stack + 1];
   R1 = g_stack_array[g_stack + 2];
   R0 = g_stack_array[g_stack + 3];
-  return g_stack_array[g_stack + FRAME_PROCEDURE];
+  g_stack_array[g_stack + FRAME_PROCEDURE];
 }
 
-SCM
-gc_pop_frame ()                 /*:((internal)) */
+void
+gc_pop_frame ()
 {
-  SCM x = gc_peek_frame ();
-  g_stack = g_stack + 5;
-  return x;
+  gc_peek_frame ();
+  g_stack = g_stack + FRAME_SIZE;
 }