diff --git a/libsrc/apple2/apple2.inc b/libsrc/apple2/apple2.inc
index d24eb8d9e..8a8321b3e 100644
--- a/libsrc/apple2/apple2.inc
+++ b/libsrc/apple2/apple2.inc
@@ -29,6 +29,7 @@ CH	=	$24
 CV	=	$25
 BASL	=	$28
 TEXTTYP	=	$32
+MEMSIZE	=	$73		; Highest free RAM location
 HOME	=	$FC58
 VTABZ	=	$FC24
 COUT    = 	$FDED
diff --git a/libsrc/apple2/crt0.s b/libsrc/apple2/crt0.s
index b1f801521..a5ed0a833 100644
--- a/libsrc/apple2/crt0.s
+++ b/libsrc/apple2/crt0.s
@@ -41,9 +41,9 @@ L1:	lda	sp,x
        	tsx
        	stx    	spsave 		; Save the system stack ptr
 
-	lda    	#<TOPMEM
+	lda    	MEMSIZE
 	sta	sp
-	lda	#>TOPMEM
+	lda	MEMSIZE+1
        	sta	sp+1   		; Set argument stack ptr
 
 ; Call module constructors