diff -Naur texstudio2.10.8.orig/pdfviewer/PDFDocument.cpp texstudio2.10.8/pdfviewer/PDFDocument.cpp
--- texstudio2.10.8.orig/pdfviewer/PDFDocument.cpp	2016-01-20 20:40:13.000000000 +0000
+++ texstudio2.10.8/pdfviewer/PDFDocument.cpp	2016-03-30 19:57:06.096666655 +0000
@@ -965,17 +965,17 @@
 
 	scrollArea->goToPage(page);
 
-	if (isnan(xinpdf)) xinpdf = 0;
+	if (std::isnan(xinpdf)) xinpdf = 0;
 	xinpdf = qBound<float>(0, xinpdf, 1);
-	if (isnan(yinpdf)) yinpdf = 0;
+	if (std::isnan(yinpdf)) yinpdf = 0;
 	yinpdf = qBound<float>(0, yinpdf, 1);
 
 	QPoint p = mapFromScaledPosition(page, QPointF( xinpdf, yinpdf));
 
-	if (!isnan(xinpdf))
+	if (!std::isnan(xinpdf))
 		scrollArea->horizontalScrollBar()->setValue(p.x());
 
-	if (!isnan(yinpdf)) {
+	if (!std::isnan(yinpdf)) {
 		int val = 0;
 		if (scrollArea->getContinuous())
 			val = scrollArea->verticalScrollBar()->value();