diff --git a/src/ripple/basics/CompressionAlgorithms.h b/src/ripple/basics/CompressionAlgorithms.h
index eb5e40b4b68..3cd67c753d8 100644
--- a/src/ripple/basics/CompressionAlgorithms.h
+++ b/src/ripple/basics/CompressionAlgorithms.h
@@ -106,6 +106,7 @@ lz4Decompress(InputStream& in, std::size_t inSize,
     std::uint8_t const* chunk = nullptr;
     int chunkSize = 0;
     int copiedInSize = 0;
+    auto const currentBytes = in.ByteCount();
 
     // Use the first chunk if it is >= inSize bytes of the compressed message.
     // Otherwise copy inSize bytes of chunks into compressed buffer and
@@ -136,8 +137,8 @@ lz4Decompress(InputStream& in, std::size_t inSize,
     }
 
     // Put back unused bytes
-    if (in.ByteCount() > copiedInSize)
-        in.BackUp(in.ByteCount() - copiedInSize);
+    if (in.ByteCount() > (currentBytes + copiedInSize))
+        in.BackUp(in.ByteCount() - currentBytes - copiedInSize);
 
     if ((copiedInSize == 0 && chunkSize < inSize) || (copiedInSize > 0 && copiedInSize != inSize))
         doThrow("lz4 decompress: insufficient input size");