diff --git a/ChainLoader.a b/ChainLoader.a
index fc9305d..8fac186 100644
--- a/ChainLoader.a
+++ b/ChainLoader.a
@@ -1,3 +1,5 @@
+kUserRecLen equ 568
+
 Code
 
 ; The ROM issued a _Read call that eventually reached here.
@@ -36,8 +38,8 @@ ResumeAfterCopy
     ; User record
             lea     gUserRec,A1
             move.l  8(SP),A0    ; global pointer
-            move.l  40(A0),A0
-            move.l  #574,D0
+            lea     46(A0),A0
+            move.l  #kUserRecLen,D0
             dc.w    $A02E ; _BlockMove
 
 
@@ -94,12 +96,12 @@ GoHereFromReadTrap
             move.w  #-52,D0 ; ioRefNum      ; also delete .ATBOOT for neatness
             dc.w    $A03E ; _DrvrRemove
 
-    ; A3 = our driver in sysheap (plus 574 bytes for the user record)
-            move.l  #DrvrEnd-DrvrBase+574,D0
+    ; A3 = our driver in sysheap (plus user record)
+            move.l  #DrvrEnd-DrvrBase+kUserRecLen,D0
             dc.w    $A51E ; NewPtrSys
             move.l  A0,A1
             lea     DrvrBase,A0
-            move.l  #DrvrEnd-DrvrBase+574,D0
+            move.l  #DrvrEnd-DrvrBase+kUserRecLen,D0
             dc.w    $A02E ; BlockMove
             move.l  A1,A3
 
@@ -717,7 +719,7 @@ DrvrIcon
             dc.l    %11111111111111111111111111111111
             dc.b    22, "AppleTalk NetBoot Disk", 0
 
-gUserRec ; append some 574 zeroes here later on
+gUserRec ; append user record here later on, no need to waste space on zeros
 
 DrvrEnd
 CodeEnd