Patch should be applied in DebugTools package too (just saying to be sure).
diff --git a/packages/debug/DebugTools.st b/packages/debug/DebugTools.st
index cb41c3b..f7f8695 100644
--- a/packages/debug/DebugTools.st
+++ b/packages/debug/DebugTools.st
@@ -48,7 +48,7 @@ pointer bytecodes to line numbers.'>
ifTrue: [MethodLineMapCache := WeakKeyIdentityDictionary new].
lineMap := MethodLineMapCache at: method
ifAbsentPut: [method sourceCodeMap].
- ^lineMap at: aContext ip + 1 ifAbsent: [1]
+ ^lineMap at: aContext ip - 1 ifAbsent: [1]
]
Debugger class>> on: aProcess [