diff --git a/screening/source/java/ch/systemsx/cisd/openbis/plugin/screening/client/web/client/application/detailviewers/WellContentDialog.java b/screening/source/java/ch/systemsx/cisd/openbis/plugin/screening/client/web/client/application/detailviewers/WellContentDialog.java
index 3492fdf7b12c2ff64cdaf3577c4e49201bb38ba2..e707cb3a7633be25485565ebad5c2356b447d0b0 100644
--- a/screening/source/java/ch/systemsx/cisd/openbis/plugin/screening/client/web/client/application/detailviewers/WellContentDialog.java
+++ b/screening/source/java/ch/systemsx/cisd/openbis/plugin/screening/client/web/client/application/detailviewers/WellContentDialog.java
@@ -76,7 +76,7 @@ public class WellContentDialog extends Dialog
                     createImageViewer(images, channelState, viewContext, imgW, imgH);
             container.add(imageViewer);
 
-            dialogWidth = imgW * images.getTileColsNum();
+            dialogWidth = imgW * Math.max(2, images.getTileColsNum());
             dialogHeight = imgH * images.getTileRowsNum() + 200;
         } else
         {