diff --git a/classpath/java-util-zip.cpp b/classpath/java-util-zip.cpp
index a7d969839a..f883e528bc 100644
--- a/classpath/java-util-zip.cpp
+++ b/classpath/java-util-zip.cpp
@@ -121,7 +121,7 @@ Java_java_util_zip_Deflater_deflate
 (JNIEnv* e, jclass, jlong peer, 
  jbyteArray input, jint inputOffset, jint inputLength,
  jbyteArray output, jint outputOffset, jint outputLength,
- jintArray results)
+ jboolean finish, jintArray results)
 {
   z_stream* s = reinterpret_cast<z_stream*>(peer);
 
@@ -145,7 +145,7 @@ Java_java_util_zip_Deflater_deflate
   s->next_out = reinterpret_cast<Bytef*>(out);
   s->avail_out = outputLength;
 
-  int r = deflate(s, Z_SYNC_FLUSH);
+  int r = deflate(s, finish ? Z_FINISH : Z_NO_FLUSH);
   jint resultArray[3]
     = { r, inputLength - s->avail_in, outputLength - s->avail_out };
 
diff --git a/classpath/java/util/zip/Deflater.java b/classpath/java/util/zip/Deflater.java
index d7bfc83b88..28df9754d2 100644
--- a/classpath/java/util/zip/Deflater.java
+++ b/classpath/java/util/zip/Deflater.java
@@ -27,14 +27,19 @@ public class Deflater {
   private boolean needDictionary;
   private boolean finished;
   private final boolean nowrap;
+  private boolean finish;
 
-  public Deflater(boolean nowrap) {
+  public Deflater(int level, boolean nowrap) {
     this.nowrap = nowrap;
-    peer = make(nowrap, DEFAULT_LEVEL);
+    peer = make(nowrap, level);
+  }
+
+  public Deflater(int level) {
+    this(level, false);
   }
 
   public Deflater() {
-    this(false);
+    this(DEFAULT_LEVEL);
   }
 
   private void check() {
@@ -85,16 +90,15 @@ public class Deflater {
     peer = make(nowrap, DEFAULT_LEVEL);
     input = null;
     offset = length = 0;
+    finish = false;
     needDictionary = finished = false;
   }
 
-  public int deflate(byte[] output) throws DataFormatException {
+  public int deflate(byte[] output) {
     return deflate(output, 0, output.length);
   }
 
-  public int deflate(byte[] output, int offset, int length)
-    throws DataFormatException
-  {
+  public int deflate(byte[] output, int offset, int length) {
     final int zlibResult = 0;
     final int inputCount = 1;
     final int outputCount = 2;
@@ -110,10 +114,10 @@ public class Deflater {
     int[] results = new int[3];
     deflate(peer, 
             input, this.offset, this.length,
-            output, offset, length, results);
+            output, offset, length, finish, results);
 
     if (results[zlibResult] < 0) {
-      throw new DataFormatException();
+      throw new AssertionError();
     }
 
     switch (results[zlibResult]) {
@@ -132,10 +136,15 @@ public class Deflater {
     return results[outputCount];
   }
 
+  public void finish() {
+    finish = true;
+  }
+
   private static native void deflate
     (long peer,
      byte[] input, int inputOffset, int inputLength,
      byte[] output, int outputOffset, int outputLength,
+     boolean finish,
      int[] results);
 
   public void dispose() {
diff --git a/classpath/java/util/zip/DeflaterOutputStream.java b/classpath/java/util/zip/DeflaterOutputStream.java
index e55668e53c..3ee3fcdbb8 100644
--- a/classpath/java/util/zip/DeflaterOutputStream.java
+++ b/classpath/java/util/zip/DeflaterOutputStream.java
@@ -52,23 +52,25 @@ public class DeflaterOutputStream extends OutputStream {
     } else if (length == 0) {
       return;
     }
-    
-    for (int i = 0; i < length; i+= buffer.length) {
-      deflater.setInput(b, offset + i, Math.min(buffer.length, length - i));
-      while (deflater.getRemaining() > 0) {
-        try {
-          int len = deflater.deflate(buffer, 0, buffer.length);
-          if (len > 0) {
-            out.write(buffer, 0, len);
-          }
-        } catch (DataFormatException e) {
-          e.printStackTrace();
-        }
-      }
+
+    deflater.setInput(b, offset, length);
+    while (deflater.getRemaining() > 0) {
+      deflate();
+    }
+  }
+
+  private void deflate() throws IOException {
+    int len = deflater.deflate(buffer, 0, buffer.length);
+    if (len > 0) {
+      out.write(buffer, 0, len);
     }
   }
 
   public void close() throws IOException {
+    deflater.finish();
+    while (! deflater.finished()) {
+      deflate();
+    }
     out.close();
     deflater.dispose();
   }