diff --git a/README.md b/README.md
index df01b55..8073081 100644
--- a/README.md
+++ b/README.md
@@ -452,6 +452,8 @@ Development (unreleased)
   The Desecration, Depreciation Log)
 - "BB00 protection" renamed to its
   marketing name "Lock-It-Up"
+- Serial numbers will be erased while
+  cracking Lock-It-Up disks, if present
 - Update Passport disk to ProDOS 2.4.2
 - Matching updates to the
   [Passport test suite](https://github.com/a2-4am/passport-test-suite)
diff --git a/src/patchers/jmpbbfe.a b/src/patchers/jmpbbfe.a
index 516cab0..96e0ce1 100755
--- a/src/patchers/jmpbbfe.a
+++ b/src/patchers/jmpbbfe.a
@@ -1,4 +1,4 @@
-;-------------------------------
+
 ; #JMPBBFE
 ; marketed as 'Lock-It-Up'
 ; boot0 jumps to ($BBFE) instead of ($08FD)
@@ -135,5 +135,29 @@ _jmpbbfe
          jsr   modify
 +        !byte $FD        ; SMC (byte offset of new entry point)
 
+         ldx   #$5E
+         ldy   #$02
+         jsr   compare    ; check for code that branches over serial number
+         !byte $D0,$05
+         bcs   .exit
+
+         inx
+         inx
+         ldy   #$05
+         jsr   compare    ; see if there is actually a non-zero serial number
+         !byte $00,$00,$00,$00,$00
+         bcc   .exit      ; passport-test-suite/Quadrilaterals.woz [C=1] here
+
+         sta   gDisplayBytes+5
+         ldy   #4
+-        lda   $1560, y
+         sta   gDisplayBytes, y
+         lda   #0
+         sta   $1560, y
+         dey
+         bpl   -
+         lda   #s_lockitupserial
+         jsr   PrintByID
+
 .exit
 }
diff --git a/src/strings/en.a b/src/strings/en.a
index 4bb280d..2fea0ee 100755
--- a/src/strings/en.a
+++ b/src/strings/en.a
@@ -164,6 +164,8 @@ StringTableLow
          !byte <.targetcffa
          !byte <.rw18
          !byte <.x555
+         !byte <.erasingserialnumber
+         !byte <.lockitupserial
 
 StringTableHigh
          !byte >.header
@@ -311,6 +313,8 @@ StringTableHigh
          !byte >.targetcffa
          !byte >.rw18
          !byte >.x555
+         !byte >.erasingserialnumber
+         !byte >.lockitupserial
 
 ;
 ; Text can contain substitution strings, which
@@ -416,6 +420,8 @@ StringTableHigh
          !text "accepts any value for the",$00
 .addressepilogue
          !text "address epilogue ",$00
+.erasingserialnumber
+         !text "Erasing serial number ",$00
 .lockitup
          !text "@",s_found,"Lock-It-Up protection",$8D
          !text "T00,S0A @",s_maybeunreadable,$8D,$00
@@ -582,7 +588,9 @@ StringTableHigh
 .decryptrwts
          !text "T00 Decrypting RWTS before writing",$8D,$00
 .protserial
-         !text "T%t,S%3 Erasing serial number %0%1%2",$8D,$00
+         !text "T%t,S%3 @",s_erasingserialnumber,"%0%1%2",$8D,$00
+.lockitupserial
+         !text "T%t,S%5 @",s_erasingserialnumber,"%0%1%2%3%4",$00
 .fbff
          !text "@",s_found,"FBFF @",s_protectioncheck,$8D,$00
 .encoded44
diff --git a/src/strings/enid.a b/src/strings/enid.a
index a4fc3e8..c29a06d 100644
--- a/src/strings/enid.a
+++ b/src/strings/enid.a
@@ -147,3 +147,5 @@ s_targetfile = $8D
 s_targetcffa = $8E
 s_rw18       = $8F
 s_555        = $90
+s_erasingserialnumber = $91
+s_lockitupserial = $92