diff --git a/src/main/java/org/msgpack/unpacker/MessagePackUnpacker.java b/src/main/java/org/msgpack/unpacker/MessagePackUnpacker.java
index e77e9237d..0a5596f39 100644
--- a/src/main/java/org/msgpack/unpacker/MessagePackUnpacker.java
+++ b/src/main/java/org/msgpack/unpacker/MessagePackUnpacker.java
@@ -210,7 +210,7 @@ private boolean readOneWithoutStackLarge(Accept a, final int b)
         case 0xc4: // bin 8
         case 0xd9: // str 8
         {
-            int count = in.getByte();
+            int count = in.getByte() & 0xff;
             if (count == 0) {
                 a.acceptEmptyRaw();
                 in.advance();