diff --git a/defines.s b/defines.s
index 6987505..d4b7f84 100644
--- a/defines.s
+++ b/defines.s
@@ -27,9 +27,7 @@ BYTES_FP		:= 4
 BYTES_FP		:= 5
 .endif
 
-.ifdef APPLE
-BYTES_PER_ELEMENT := 6 ; ???
-.else
+.ifndef BYTES_PER_ELEMENT
 BYTES_PER_ELEMENT := BYTES_FP
 .endif
 BYTES_PER_VARIABLE := BYTES_FP+2
@@ -38,9 +36,7 @@ BYTES_PER_FRAME := 2*BYTES_FP+8
 FOR_STACK1		:= 2*BYTES_FP+5
 FOR_STACK2		:= BYTES_FP+4
 
-.ifdef CBM1
-MAX_EXPON = 12
-.else
+.ifndef MAX_EXPON
 MAX_EXPON = 10
 .endif
 
diff --git a/defines_apple.s b/defines_apple.s
index f8a469f..29f5826 100644
--- a/defines_apple.s
+++ b/defines_apple.s
@@ -7,6 +7,8 @@ CONFIG_PRINT_CR := 1 ; print CR when line end reached
 CONFIG_SAFE_NAMENOTFOUND := 1
 CONFIG_SCRTCH_ORDER := 3
 
+BYTES_PER_ELEMENT := 6 ; XXX override
+
 ; zero page
 ZP_START0 = $00
 ZP_START0A = $4F
diff --git a/defines_cbm.s b/defines_cbm.s
index d996b9c..23cae25 100644
--- a/defines_cbm.s
+++ b/defines_cbm.s
@@ -63,6 +63,7 @@ INPUTBUFFER     := $0200
 SPACE_FOR_GOSUB := $36
 STACK_TOP		:= $FC
 NULL_MAX		:= $0A
+MAX_EXPON		:= 12 ; XXX override
 .else
 SPACE_FOR_GOSUB := $3E
 STACK_TOP		:= $FA