diff --git a/src/org/thialfihar/android/apg/Apg.java b/src/org/thialfihar/android/apg/Apg.java
index bc21487fa..e290a501e 100644
--- a/src/org/thialfihar/android/apg/Apg.java
+++ b/src/org/thialfihar/android/apg/Apg.java
@@ -1527,7 +1527,8 @@ public class Apg {
     }
 
     public static Bundle decrypt(Context context,
-                                 InputStream inStream, OutputStream outStream,
+                                 PositionAwareInputStream inStream, OutputStream outStream,
+                                 long dataLength,
                                  String passPhrase, ProgressDialogUpdater progress,
                                  boolean assumeSymmetric)
             throws IOException, GeneralException, PGPException, SignatureException {
@@ -1685,6 +1686,7 @@ public class Apg {
             }
             int n = 0;
             int done = 0;
+            long startPos = inStream.position();
             while ((n = dataIn.read(buffer)) > 0) {
                 out.write(buffer, 0, n);
                 done += n;
@@ -1698,6 +1700,12 @@ public class Apg {
                 }
                 // unknown size, but try to at least have a moving, slowing down progress bar
                 currentProgress = startProgress + (endProgress - startProgress) * done / (done + 100000);
+                if (dataLength - startPos == 0) {
+                    currentProgress = endProgress;
+                } else {
+                    currentProgress = (int)(startProgress + (endProgress - startProgress) *
+                                        (inStream.position() - startPos) / (dataLength - startPos));
+                }
                 progress.setProgress(currentProgress, 100);
             }
 
diff --git a/src/org/thialfihar/android/apg/DecryptActivity.java b/src/org/thialfihar/android/apg/DecryptActivity.java
index b34bbba49..7e31e5f90 100644
--- a/src/org/thialfihar/android/apg/DecryptActivity.java
+++ b/src/org/thialfihar/android/apg/DecryptActivity.java
@@ -436,21 +436,26 @@ public class DecryptActivity extends BaseActivity {
         Message msg = new Message();
 
         try {
-            InputStream in = null;
+            PositionAwareInputStream in = null;
             OutputStream out = null;
+            long size = 0;
+
             if (mDecryptTarget == Id.target.message) {
                 String messageData = mMessage.getText().toString();
-                in = new ByteArrayInputStream(messageData.getBytes());
+                in = new PositionAwareInputStream(new ByteArrayInputStream(messageData.getBytes()));
                 out = new ByteArrayOutputStream();
+                size = messageData.getBytes().length;
             } else {
-                in = new FileInputStream(mInputFilename);
+                in = new PositionAwareInputStream(new FileInputStream(mInputFilename));
                 out = new FileOutputStream(mOutputFilename);
+                File file = new File(mInputFilename);
+                size = file.length();
             }
 
             if (mSignedOnly) {
                 data = Apg.verifyText(this, in, out, this);
             } else {
-                data = Apg.decrypt(this, in, out, Apg.getCachedPassPhrase(getSecretKeyId()),
+                data = Apg.decrypt(this, in, out, size, Apg.getCachedPassPhrase(getSecretKeyId()),
                                    this, mAssumeSymmetricEncryption);
             }
 
diff --git a/src/org/thialfihar/android/apg/PositionAwareInputStream.java b/src/org/thialfihar/android/apg/PositionAwareInputStream.java
new file mode 100644
index 000000000..661e053f2
--- /dev/null
+++ b/src/org/thialfihar/android/apg/PositionAwareInputStream.java
@@ -0,0 +1,67 @@
+package org.thialfihar.android.apg;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+public class PositionAwareInputStream extends InputStream {
+    private InputStream mStream;
+    private long mPosition;
+
+    public PositionAwareInputStream(InputStream in) {
+        mStream = in;
+        mPosition = 0;
+    }
+
+    @Override
+    public int read() throws IOException {
+        int ch = mStream.read();
+        ++mPosition;
+        return ch;
+    }
+
+    @Override
+    public int available() throws IOException {
+        return mStream.available();
+    }
+
+    @Override
+    public void close() throws IOException {
+        mStream.close();
+    }
+
+    @Override
+    public boolean markSupported() {
+        return false;
+    }
+
+    @Override
+    public int read(byte[] b) throws IOException {
+        int result = mStream.read(b);
+        mPosition += result;
+        return result;
+    }
+
+    @Override
+    public int read(byte[] b, int offset, int length) throws IOException {
+        int result = mStream.read(b, offset, length);
+        mPosition += result;
+        return result;
+    }
+
+    @Override
+    public synchronized void reset() throws IOException {
+        mStream.reset();
+        mPosition = 0;
+    }
+
+    @Override
+    public long skip(long n) throws IOException {
+        long result = mStream.skip(n);
+        mPosition += result;
+        return result;
+    }
+
+    public long position() {
+        return mPosition;
+    }
+}