diff --git a/common/rdr/MemInStream.h b/common/rdr/MemInStream.h
new file mode 100644
index 0000000..77ca3f3
--- /dev/null
+++ b/common/rdr/MemInStream.h
@@ -0,0 +1,63 @@
+/* Copyright (C) 2002-2005 RealVNC Ltd.  All Rights Reserved.
+ * 
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this software; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
+ * USA.
+ */
+
+//
+// rdr::MemInStream is an InStream which streams from a given memory buffer.
+// If the deleteWhenDone parameter is true then the buffer will be delete[]d in
+// the destructor.  Note that it is delete[]d as a U8* - strictly speaking this
+// means it ought to be new[]ed as a U8* as well, but on most platforms this
+// doesn't matter.
+//
+
+#ifndef __RDR_MEMINSTREAM_H__
+#define __RDR_MEMINSTREAM_H__
+
+#include <rdr/InStream.h>
+#include <rdr/Exception.h>
+
+namespace rdr {
+
+  class MemInStream : public InStream {
+
+  public:
+
+    MemInStream(const void* data, int len, bool deleteWhenDone_=false)
+      : start((const U8*)data), deleteWhenDone(deleteWhenDone_)
+    {
+      ptr = start;
+      end = start + len;
+    }
+
+    virtual ~MemInStream() {
+      if (deleteWhenDone)
+        delete [] (U8*)start;
+    }
+
+    int pos() { return ptr - start; }
+    void reposition(int pos) { ptr = start + pos; }
+
+  private:
+
+    int overrun(int itemSize, int nItems, bool wait) { throw EndOfStream(); }
+    const U8* start;
+    bool deleteWhenDone;
+  };
+
+}
+
+#endif