diff --git a/src/patchers/ssprot.a b/src/patchers/ssprot.a
index 7a6565e..d1d98af 100644
--- a/src/patchers/ssprot.a
+++ b/src/patchers/ssprot.a
@@ -17,9 +17,9 @@
 ;-------------------------------
 !zone {
          bit   gMode      ; nothing to do here in verify-only mode
-         bpl   .exit
+         bpl   .exit0
          lda   gIsF7F6
-         bne   .exit
+         bne   .exit0
          lda   #$0F
          sta   .sector+1
 .sector  lda   #$FF                  ; modified above
@@ -46,14 +46,22 @@
          ldy   #$03
          jsr   compare
          !byte $23,$2A,$28
-         bcc   .variant1  ; passport-test-suite/Creative Contraptions.woz [C=0] matches
+         bcc   .variant1             ; passport-test-suite/Creative Contraptions.woz [C=0] matches
 
          ldy   #$03
          jsr   compare
          !byte $70,$79,$77
-         bcc   .variant2  ; passport-test-suite/Wortgefecht.woz [C=0] matches
+         bcc   .variant2             ; passport-test-suite/Wortgefecht.woz [C=0] matches
+
+         ldy   #$03
+         jsr   compare
+         !byte $23,$2A,$24           ; passport-test-suite/Metric System Tutor.woz [C=0] matches
+         bcc   .variant3
          bcs   .nextsector
 
+.exit0   jmp   .exit
+.sector0 bpl   .sector
+
 .variant1
          ldx   #$20
          ldy   #$03
@@ -77,10 +85,19 @@
          jsr   modify                ; new JMP entry point ($0903 when decrypted)
          !byte $FA,$F2
 
-; note: execution falls through here
+.variant3
+         ldx   #$20
+         ldy   #$03
+         jsr   modify
+         !byte $EA                   ; NOP
+         !byte $A9,$27               ; LDA #$27
+         ldx   #$76
+         ldy   #$02
+         jsr   modify                ; new JMP entry point ($0903 when decrypted)
+         !byte $A9,$A1
 
 .nextsector
          dec   .sector+1
-         bpl   .sector
+         bpl   .sector0
 .exit
 }