diff --git a/autotests/kcompressiondevicetest.h b/autotests/kcompressiondevicetest.h
--- a/autotests/kcompressiondevicetest.h
+++ b/autotests/kcompressiondevicetest.h
@@ -58,6 +58,7 @@
     void testWriteErrorOnOpen();
     void testWriteErrorOnClose();
 
+    void testSeekReadUncompressedBuffer_data();
     void testSeekReadUncompressedBuffer();
 };
 
diff --git a/autotests/kcompressiondevicetest.cpp b/autotests/kcompressiondevicetest.cpp
--- a/autotests/kcompressiondevicetest.cpp
+++ b/autotests/kcompressiondevicetest.cpp
@@ -192,25 +192,35 @@
     QCOMPARE(int(dev.error()), int(QFileDevice::WriteError));
 }
 
+void KCompressionDeviceTest::testSeekReadUncompressedBuffer_data()
+{
+    QTest::addColumn<int>("dataSize");
+    QTest::addColumn<int>("realDataPos");
+    QTest::newRow("1.5buffer") << BUFFER_SIZE + BUFFER_SIZE / 2 << BUFFER_SIZE;
+    QTest::newRow("5seekbuffer") << 5 * SEEK_BUFFER_SIZE << 4 * SEEK_BUFFER_SIZE;
+}
+
 void KCompressionDeviceTest::testSeekReadUncompressedBuffer()
 {
-    const int dataSize = BUFFER_SIZE + BUFFER_SIZE / 2;
+    QFETCH(int, dataSize);
+    QFETCH(int, realDataPos);
+
     QByteArray ba(dataSize, 0);
 
-    // all data is zero except after BUFFER_SIZE that it's 0 to 9
+    // all data is zero except after realDataPos that it's 0 to 9
     for (int i = 0; i < 10; ++i) {
-        ba[BUFFER_SIZE + i] = i;
+        ba[realDataPos + i] = i;
     }
 
     QBuffer b;
     b.setData(ba);
     QVERIFY(b.open(QIODevice::ReadOnly));
 
     KCompressionDevice kcd(&b, false, KCompressionDevice::GZip);
     QVERIFY(kcd.open(QIODevice::ReadOnly));
-    QVERIFY(kcd.seek(BUFFER_SIZE));
+    QVERIFY(kcd.seek(realDataPos));
 
-    // the 10 bytes after BUFFER_SIZE should be 0 to 9
+    // the 10 bytes after realDataPos should be 0 to 9
     const QByteArray kcdData = kcd.read(10);
     QCOMPARE(kcdData.size(), 10);
     for (int i = 0; i < kcdData.size(); ++i) {
diff --git a/src/kcompressiondevice.cpp b/src/kcompressiondevice.cpp
--- a/src/kcompressiondevice.cpp
+++ b/src/kcompressiondevice.cpp
@@ -246,9 +246,16 @@
     }
 
     //qCDebug(KArchiveLog) << "reading " << bytesToRead << " dummy bytes";
-    QByteArray dummy(qMin(bytesToRead, qint64(3 * BUFFER_SIZE)), 0);
-    const bool result = (read(dummy.data(), bytesToRead) == bytesToRead);
-    return result;
+    QByteArray dummy(qMin(bytesToRead, qint64(SEEK_BUFFER_SIZE)), 0);
+    while (bytesToRead > 0) {
+        const qint64 bytesToReadThisTime = qMin(bytesToRead, qint64(dummy.size()));
+        const bool result = (read(dummy.data(), bytesToReadThisTime) == bytesToReadThisTime);
+        if (!result) {
+            return false;
+        }
+        bytesToRead -= bytesToReadThisTime;
+    }
+    return true;
 }
 
 bool KCompressionDevice::atEnd() const
diff --git a/src/kcompressiondevice_p.h b/src/kcompressiondevice_p.h
--- a/src/kcompressiondevice_p.h
+++ b/src/kcompressiondevice_p.h
@@ -20,5 +20,6 @@
 #define __kcompressiondevice_p_h
 
 #define BUFFER_SIZE 8*1024
+#define SEEK_BUFFER_SIZE 3*BUFFER_SIZE
 
 #endif