--- misc/libvisio-0.0.17/src/lib/VSDXContentCollector.cpp	2012-05-31 15:14:42.000000000 +0200
+++ misc/build/libvisio-0.0.17/src/lib/VSDXContentCollector.cpp	2012-06-09 00:08:24.139051461 +0200
@@ -1429,7 +1429,10 @@ void libvisio::VSDXContentCollector::collectNURBSTo(unsigned /* id */, unsigned
 
   // Fill in end knots
   while (knotVector.size() < (controlPoints.size() + degree + 2))
-    knotVector.push_back(knotVector.back());
+  {
+    double tmpBack = knotVector.back();
+    knotVector.push_back(tmpBack);
+  }
 
   // Convert control points to static co-ordinates
   for (std::vector<std::pair<double, double> >::iterator it = controlPoints.begin();
@@ -2059,7 +2062,11 @@
 
 void libvisio::VSDXContentCollector::_convertDataToString(WPXString &result, const WPXBinaryData &data, TextFormat format)
 {
+  if (!data.size())
+    return;
   WPXInputStream *pStream = const_cast<WPXInputStream *>(data.getDataStream());
+  if (!pStream)
+    return;
   if (format == VSD_TEXT_ANSI)
   {
     while (!pStream->atEOS())
@@ -2312,6 +2312,8 @@ void libvisio::VSDXContentCollector::endPages(const std::vector<unsigned> &pageO
 
 void libvisio::VSDXContentCollector::_appendUTF16LE(WPXString &text, WPXInputStream *input)
 {
+  if (!input)
+    return;
   while (!input->atEOS())
   {
     uint16_t high_surrogate = 0;