diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/util/io/StreamCopyThread.java b/org.eclipse.jgit/src/org/eclipse/jgit/util/io/StreamCopyThread.java
index a2b954017..50f42ad4f 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/util/io/StreamCopyThread.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/util/io/StreamCopyThread.java
@@ -47,6 +47,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.InterruptedIOException;
 import java.io.OutputStream;
+import java.util.concurrent.atomic.AtomicInteger;
 
 /** Thread to copy from an input stream to an output stream. */
 public class StreamCopyThread extends Thread {
@@ -56,7 +57,7 @@ public class StreamCopyThread extends Thread {
 
 	private final OutputStream dst;
 
-	private volatile boolean doFlush;
+	private final AtomicInteger flushCounter = new AtomicInteger(0);
 
 	/**
 	 * Create a thread to copy data from an input stream to an output stream.
@@ -82,10 +83,8 @@ public class StreamCopyThread extends Thread {
 	 * the request.
 	 */
 	public void flush() {
-		if (!doFlush) {
-			doFlush = true;
-			interrupt();
-		}
+		flushCounter.incrementAndGet();
+		interrupt();
 	}
 
 	@Override
@@ -94,10 +93,8 @@ public class StreamCopyThread extends Thread {
 			final byte[] buf = new byte[BUFFER_SIZE];
 			for (;;) {
 				try {
-					if (doFlush) {
-						doFlush = false;
+					if (needFlush())
 						dst.flush();
-					}
 
 					final int n;
 					try {
@@ -125,4 +122,13 @@ public class StreamCopyThread extends Thread {
 			}
 		}
 	}
+
+	private boolean needFlush() {
+		int i = flushCounter.get();
+		if (i > 0) {
+			flushCounter.decrementAndGet();
+			return true;
+		}
+		return false;
+	}
 }