diff --git a/src/xenia/base/bit_stream.cc b/src/xenia/base/bit_stream.cc
index ce74937dd..98a53af15 100644
--- a/src/xenia/base/bit_stream.cc
+++ b/src/xenia/base/bit_stream.cc
@@ -2,7 +2,7 @@
  ******************************************************************************
  * Xenia : Xbox 360 Emulator Research Project                                 *
  ******************************************************************************
- * Copyright 2015 Ben Vanik. All rights reserved.                             *
+ * Copyright 2021 Ben Vanik. All rights reserved.                             *
  * Released under the BSD license - see LICENSE in the root for more details. *
  ******************************************************************************
  */
@@ -111,6 +111,8 @@ size_t BitStream::Copy(uint8_t* dest_buffer, size_t num_bits) {
   // First: Copy the first few bits up to a byte boundary.
   if (rel_offset_bits) {
     uint64_t bits = Peek(8 - rel_offset_bits);
+    uint8_t clear_mask = ~((uint8_t(1) << rel_offset_bits) - 1);
+    dest_buffer[out_offset_bytes] &= clear_mask;
     dest_buffer[out_offset_bytes] |= (uint8_t)bits;
 
     bits_left -= 8 - rel_offset_bits;
@@ -132,6 +134,8 @@ size_t BitStream::Copy(uint8_t* dest_buffer, size_t num_bits) {
     uint64_t bits = Peek(bits_left);
     bits <<= 8 - bits_left;
 
+    uint8_t clear_mask = ((uint8_t(1) << bits_left) - 1);
+    dest_buffer[out_offset_bytes] &= clear_mask;
     dest_buffer[out_offset_bytes] |= (uint8_t)bits;
     Advance(bits_left);
   }