diff --git a/src/protocol_muxer/multiselect/parser.cpp b/src/protocol_muxer/multiselect/parser.cpp
index 39f35c91..8c9049a2 100644
--- a/src/protocol_muxer/multiselect/parser.cpp
+++ b/src/protocol_muxer/multiselect/parser.cpp
@@ -44,8 +44,12 @@ namespace libp2p::protocol_muxer::multiselect::detail {
 
       if (expected_msg_size_ == 0) {
         auto s = varint_reader_.consume(data);
+        if (varint_reader_.size() > kMaxLenBytes) {
+          state_ = kOverflow;
+          break;
+        }
         if (s == VarintPrefixReader::kUnderflow) {
-          if (varint_reader_.size() >= kMaxLenBytes) {
+          if (varint_reader_.size() == kMaxLenBytes) {
             state_ = kOverflow;
             break;
           }
@@ -55,10 +59,6 @@ namespace libp2p::protocol_muxer::multiselect::detail {
           state_ = kOverflow;
           break;
         }
-        if (varint_reader_.size() > kMaxLenBytes) {
-          state_ = kOverflow;
-          break;
-        }
         expected_msg_size_ = static_cast<IndexType>(varint_reader_.value());
         if (expected_msg_size_ == 0) {
           // zero varint received, not acceptable, but not fatal