diff --git a/src/main/java/org/apache/hadoop/fs/cosn/buffer/CosNByteBuffer.java b/src/main/java/org/apache/hadoop/fs/cosn/buffer/CosNByteBuffer.java
index a9d767c2..246ce0cd 100644
--- a/src/main/java/org/apache/hadoop/fs/cosn/buffer/CosNByteBuffer.java
+++ b/src/main/java/org/apache/hadoop/fs/cosn/buffer/CosNByteBuffer.java
@@ -23,7 +23,7 @@ public CosNByteBuffer(ByteBuffer byteBuffer) {
     }
 
     public CosNByteBuffer put(byte b) throws IOException {
-        if (this.byteBuffer.hasRemaining()) {
+        if (!this.byteBuffer.hasRemaining()) {
             throw new IOException("There is no remaining in the buffer.");
         }
         this.byteBuffer.put(b);