diff --git a/core/src/main/scala/org/apache/spark/util/io/ChunkedByteBufferOutputStream.scala b/core/src/main/scala/org/apache/spark/util/io/ChunkedByteBufferOutputStream.scala
index a625b32895..34d36655a6 100644
--- a/core/src/main/scala/org/apache/spark/util/io/ChunkedByteBufferOutputStream.scala
+++ b/core/src/main/scala/org/apache/spark/util/io/ChunkedByteBufferOutputStream.scala
@@ -48,7 +48,7 @@ private[spark] class ChunkedByteBufferOutputStream(
    * This can also never be 0.
    */
   private[this] var position = chunkSize
-  private[this] var _size = 0
+  private[this] var _size = 0L
   private[this] var closed: Boolean = false
 
   def size: Long = _size
@@ -120,4 +120,5 @@ private[spark] class ChunkedByteBufferOutputStream(
       new ChunkedByteBuffer(ret)
     }
   }
+
 }
diff --git a/core/src/test/scala/org/apache/spark/util/io/ChunkedByteBufferOutputStreamSuite.scala b/core/src/test/scala/org/apache/spark/util/io/ChunkedByteBufferOutputStreamSuite.scala
index 8696174567..29443e275f 100644
--- a/core/src/test/scala/org/apache/spark/util/io/ChunkedByteBufferOutputStreamSuite.scala
+++ b/core/src/test/scala/org/apache/spark/util/io/ChunkedByteBufferOutputStreamSuite.scala
@@ -119,4 +119,14 @@ class ChunkedByteBufferOutputStreamSuite extends SparkFunSuite {
     assert(arrays(1).toSeq === ref.slice(10, 20))
     assert(arrays(2).toSeq === ref.slice(20, 30))
   }
+
+  test("SPARK-36464: size returns correct positive number even with over 2GB data") {
+    val ref = new Array[Byte](1024 * 1024 * 1024)
+    val o = new ChunkedByteBufferOutputStream(1024 * 1024, ByteBuffer.allocate)
+    o.write(ref)
+    o.write(ref)
+    o.close()
+    assert(o.size > 0L) // make sure it is not overflowing
+    assert(o.size == ref.length.toLong * 2)
+  }
 }