diff --git a/Assets/PerfectWorld/Scripts/Network/CSNetwork/Security/StreamCompress.cs b/Assets/PerfectWorld/Scripts/Network/CSNetwork/Security/StreamCompress.cs
index 7b327c9974..b2b7f20450 100644
--- a/Assets/PerfectWorld/Scripts/Network/CSNetwork/Security/StreamCompress.cs
+++ b/Assets/PerfectWorld/Scripts/Network/CSNetwork/Security/StreamCompress.cs
@@ -146,9 +146,16 @@ namespace CSNetwork.Security
                 {
                     if (!PassBits(8))
                         break;
+                    // Defer if writing this literal would cross the end of the linear window.
+                    // We only wrap at EOB to match the original C++ semantics.
+                    if (historyPos + 1 > MPPC_HIST_LEN)
+                    {
+                        bitPos = adjust_bitPos;
+                        readPos = adjust_readPos;
+                        break;
+                    }
                     history[historyPos++] = (byte)(val >> 24);
-                    if (historyPos == MPPC_HIST_LEN)
-                        historyPos = 0;
+                    // Do not wrap here; wrapping is handled only at EOB.
                     continue;
                 }
 
@@ -156,9 +163,15 @@ namespace CSNetwork.Security
                 {
                     if (!PassBits(9))
                         break;
+                    // Defer if writing this literal would cross the end of the linear window.
+                    if (historyPos + 1 > MPPC_HIST_LEN)
+                    {
+                        bitPos = adjust_bitPos;
+                        readPos = adjust_readPos;
+                        break;
+                    }
                     history[historyPos++] = (byte)(((val >> 23) | 0x80) & 0xFF);
-                    if (historyPos == MPPC_HIST_LEN)
-                        historyPos = 0;
+                    // Do not wrap here; wrapping is handled only at EOB.
                     continue;
                 }
 
@@ -316,19 +329,19 @@ namespace CSNetwork.Security
                     break;
                 }
 
-                // Perform match copy in the 8 KB circular history buffer.
-                // Valid offsets are in 1..MPPC_HIST_LEN; offset==0 would be EOB (handled above).
-                if (offset == 0 || offset > MPPC_HIST_LEN)
+                // Validate match boundaries against the current linear window. Defer if it would cross.
+                // This mirrors the C++ check: if (histptr - off < history || histptr + len > history + MPPC_HIST_LEN) break;
+                if (offset == 0 || offset > MPPC_HIST_LEN || historyPos - (int)offset < 0 || historyPos + (int)length > MPPC_HIST_LEN)
                 {
-                    // Invalid backreference relative to the sliding window; defer until more data
-                    // by restoring bit/read positions to the last safe checkpoint.
+                    // Not enough room in the current linear window; rollback and wait for more data.
                     bitPos = adjust_bitPos;
                     readPos = adjust_readPos;
                     break;
                 }
 
-                // Circular, overlap-safe copy as required by MPPC (LZ77-style) semantics.
-                CopyFromHistoryCircular((int)offset, (int)length);
+                // Linear, overlap-safe copy within current window. No mid-block wrap.
+                LameCopy(historyPos, historyPos - (int)offset, (int)length);
+                historyPos += (int)length;
             }
 
             // Copy remaining history segment to output