diff -r fcece45ef507 -r 79de32ba3296 src/corelib/io/qiodevice.cpp
--- a/src/corelib/io/qiodevice.cpp	Mon May 03 13:17:34 2010 +0300
+++ b/src/corelib/io/qiodevice.cpp	Fri May 14 16:40:13 2010 +0300
@@ -755,6 +755,7 @@
 qint64 QIODevice::read(char *data, qint64 maxSize)
 {
     Q_D(QIODevice);
+    CHECK_READABLE(read, qint64(-1));
 
 #if defined QIODEVICE_DEBUG
     printf("%p QIODevice::read(%p, %d), d->pos = %d, d->buffer.size() = %d\n",