diff -ur kdiff3-0.9.95/src-QT4/difftextwindow.cpp kdiff3-0.9.95/src-QT4/difftextwindow.cpp
--- kdiff3-0.9.95/src-QT4/difftextwindow.cpp	2009-02-08 20:46:46.000000000 +0100
+++ kdiff3-0.9.95/src-QT4/difftextwindow.cpp	2009-11-22 02:05:04.000000000 +0100
@@ -1089,7 +1093,8 @@
 
 void DiffTextWindowData::draw( MyPainter& p, const QRect& invalidRect, int deviceWidth, int beginLine, int endLine )
 {
-   m_lineNumberWidth =  m_pOptionDialog->m_bShowLineNumbers ? (int)log10((double)m_size)+1 : 0;
+   m_lineNumberWidth = (m_pOptionDialog->m_bShowLineNumbers && m_size > 0)
+                     ? (int)log10((double)m_size)+1 : 0;
 
    if ( m_winIdx==1 )
    {
@@ -1754,7 +1759,8 @@
    if ( pDTW && pDTW->d->m_pDiff3LineVector )
    {
       QString s= i18n("Top line");
-      int lineNumberWidth = (int)log10((double)pDTW->d->m_size)+1;
+      int lineNumberWidth = pDTW->d->m_size > 0
+                          ? (int)log10((double)pDTW->d->m_size)+1 : 0;
 
       int l=pDTW->calcTopLineInFile(firstLine);