diff --git a/include/mes/constants.h b/include/mes/constants.h
index 3f86c6cf..42424390 100644
--- a/include/mes/constants.h
+++ b/include/mes/constants.h
@@ -68,10 +68,10 @@
 // CONSTANT STRUCT_PRINTER 1
 #define STRUCT_PRINTER 1
 
-// CONSTANT FRAME_SIZE 5
-#define FRAME_SIZE 5
-// CONSTANT FRAME_PROCEDURE 4
-#define FRAME_PROCEDURE 4
+// CONSTANT GC_FRAME_SIZE 5
+#define GC_FRAME_SIZE 5
+// CONSTANT GC_FRAME_PROCEDURE 4
+#define GC_FRAME_PROCEDURE 4
 
 // CONSTANT STDIN 0
 // CONSTANT STDOUT 1
diff --git a/src/eval-apply.c b/src/eval-apply.c
index d0a8a463..bd09cb30 100644
--- a/src/eval-apply.c
+++ b/src/eval-apply.c
@@ -441,7 +441,7 @@ evlis3:
   goto vm_return;
 
 apply:
-  g_stack_array[g_stack + FRAME_PROCEDURE] = R1->car;
+  g_stack_array[g_stack + GC_FRAME_PROCEDURE] = R1->car;
   a = R1->car;
   t = a->type;
   if (t == TSTRUCT && builtin_p (R1->car) == cell_t)
diff --git a/src/gc.c b/src/gc.c
index 55e4dec3..62643bbc 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -694,14 +694,14 @@ gc ()
 void
 gc_push_frame ()
 {
-  if (g_stack < FRAME_SIZE)
+  if (g_stack < GC_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 - FRAME_SIZE;
+  g_stack = g_stack - GC_FRAME_SIZE;
 }
 
 void
@@ -711,14 +711,14 @@ gc_peek_frame ()
   R2 = g_stack_array[g_stack + 1];
   R1 = g_stack_array[g_stack + 2];
   R0 = g_stack_array[g_stack + 3];
-  g_stack_array[g_stack + FRAME_PROCEDURE];
+  g_stack_array[g_stack + GC_FRAME_PROCEDURE];
 }
 
 void
 gc_pop_frame ()
 {
   gc_peek_frame ();
-  g_stack = g_stack + FRAME_SIZE;
+  g_stack = g_stack + GC_FRAME_SIZE;
 }
 
 void
diff --git a/src/stack.c b/src/stack.c
index 6fc25fb1..02d58f7c 100644
--- a/src/stack.c
+++ b/src/stack.c
@@ -53,8 +53,8 @@ make_frame (struct scm *stack, long index)
   struct scm *procedure = 0;
   if (index != 0)
     {
-      array_index = (STACK_SIZE - (index * FRAME_SIZE));
-      procedure = g_stack_array[array_index + FRAME_PROCEDURE];
+      array_index = (STACK_SIZE - (index * GC_FRAME_SIZE));
+      procedure = g_stack_array[array_index + GC_FRAME_PROCEDURE];
     }
   if (procedure == 0)
     procedure = cell_f;
@@ -78,7 +78,7 @@ struct scm *
 make_stack (struct scm *stack)          /*:((arity . n)) */
 {
   struct scm *stack_type = make_stack_type ();
-  long size = (STACK_SIZE - g_stack) / FRAME_SIZE;
+  long size = (STACK_SIZE - g_stack) / GC_FRAME_SIZE;
   struct scm *frames = make_vector_ (size, cell_unspecified);
   long i;
   struct scm* frame;