diff --git a/uk/ac/sanger/artemis/components/alignment/CoveragePanel.java b/uk/ac/sanger/artemis/components/alignment/CoveragePanel.java
index 1f46780d70fc8fc894576d8c44ef07cc24b6b8b1..d1351c3636ded21df9769909288d2a355a3a38c2 100644
--- a/uk/ac/sanger/artemis/components/alignment/CoveragePanel.java
+++ b/uk/ac/sanger/artemis/components/alignment/CoveragePanel.java
@@ -387,7 +387,7 @@ import net.sf.samtools.SAMRecord;
           continue;
 
         g2.setColor(definedColours[ colourIdx ]);
-        g2.fillRect(xpos, plotPos, windowSize, plotHgt);
+        g2.fillRect(xpos, plotPos, (int) (windowSize*2*pixPerBase), plotHgt);
       }
     }