diff --git a/src/openrct2/rct12/SawyerChunkReader.cpp b/src/openrct2/rct12/SawyerChunkReader.cpp
index b242b94572..b94c0ed3ce 100644
--- a/src/openrct2/rct12/SawyerChunkReader.cpp
+++ b/src/openrct2/rct12/SawyerChunkReader.cpp
@@ -115,7 +115,7 @@ void SawyerChunkReader::ReadChunk(void * dst, size_t length)
     }
     else
     {
-        std::copy_n(chunkData, length, (uint8 *)dst);
+        std::copy_n(chunkData, chunkLength, (uint8 *)dst);
         auto remainingLength = length - chunkLength;
         if (remainingLength > 0)
         {