diff --git a/src/apple2/penetrator.cfg b/src/apple2/penetrator.cfg
index 51d5ca9..a907e48 100644
--- a/src/apple2/penetrator.cfg
+++ b/src/apple2/penetrator.cfg
@@ -3,7 +3,7 @@ SYMBOLS {
     __FILETYPE__: type  = export, value = $0006;
 }
 MEMORY {
-    ZP:     file = "",               start = $0050,         size = $00FF-$0050;
+    ZP:     file = "",               start = $0050,         size = $0100 - $0050;
     HEADER: file = %O,               start = $4000 - $003A, size = $003A;
     MAIN:   file = %O, define = yes, start = $4000,         size = $BF00 - $4000;
     BSS:    file = "",               start = $0800,         size = $2000 - $0800;