From d4010ad278406da05ece41355eb3b20ddeeb4b1b Mon Sep 17 00:00:00 2001
From: Sam Alws <sam.alws@trailofbits.com>
Date: Tue, 11 Apr 2023 13:35:37 -0400
Subject: [PATCH] fix srcMapCodePos

---
 CHANGELOG.md     | 1 +
 src/EVM/Debug.hs | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index af1005dcf..0c398472c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - The `prank` cheatcode now transfers value from the correct address
+- Fixed an off-by-one error in `EVM.Debug.srcMapCodePos`
 
 ## [0.50.4] - 2023-03-17
 
diff --git a/src/EVM/Debug.hs b/src/EVM/Debug.hs
index 504bdd3aa..513cc3723 100644
--- a/src/EVM/Debug.hs
+++ b/src/EVM/Debug.hs
@@ -47,7 +47,7 @@ srcMapCodePos :: SourceCache -> SrcMap -> Maybe (Text, Int)
 srcMapCodePos cache sm =
   fmap (second f) $ cache.files ^? ix sm.file
   where
-    f v = ByteString.count 0xa (ByteString.take (sm.offset - 1) v) + 1
+    f v = ByteString.count 0xa (ByteString.take sm.offset v) + 1
 
 srcMapCode :: SourceCache -> SrcMap -> Maybe ByteString
 srcMapCode cache sm =