diff --git a/screening/source/java/ch/systemsx/cisd/openbis/dss/generic/server/images/ImageChannelsUtils.java b/screening/source/java/ch/systemsx/cisd/openbis/dss/generic/server/images/ImageChannelsUtils.java
index 1b2e134095430dcc9c56354051d5a897f25fd60b..202a642c4907853d4f98842ba0144022d3a6803e 100644
--- a/screening/source/java/ch/systemsx/cisd/openbis/dss/generic/server/images/ImageChannelsUtils.java
+++ b/screening/source/java/ch/systemsx/cisd/openbis/dss/generic/server/images/ImageChannelsUtils.java
@@ -232,7 +232,7 @@ public class ImageChannelsUtils
         {
             throw EnvironmentFailureException.fromTemplate("No "
                     + (thumbnailSizeOrNull != null ? "thumbnail" : "image")
-                    + " found for well %s, tile %s and channel %d", wellLocation, tileLocation,
+                    + " found for well %s, tile %s and channel %s", wellLocation, tileLocation,
                     chosenChannel);
         }
     }