diff --git a/screening/source/java/ch/systemsx/cisd/openbis/dss/generic/server/AbstractImagesDownloadServlet.java b/screening/source/java/ch/systemsx/cisd/openbis/dss/generic/server/AbstractImagesDownloadServlet.java
index fb2200c43560598224b81a5f7e5d33dbc66ea28a..6acf38a41bb27d0e042e6d24d53c7b7d2eb4abcd 100644
--- a/screening/source/java/ch/systemsx/cisd/openbis/dss/generic/server/AbstractImagesDownloadServlet.java
+++ b/screening/source/java/ch/systemsx/cisd/openbis/dss/generic/server/AbstractImagesDownloadServlet.java
@@ -75,7 +75,7 @@ abstract class AbstractImagesDownloadServlet extends AbstractDatasetDownloadServ
 
         private RequestParams(HttpServletRequest request)
         {
-            this.sessionId = getParam(request, SESSION_ID_PARAM);
+            this.sessionId = getParam(request, Utils.SESSION_ID_PARAM);
 
             String displayModeText = request.getParameter(DISPLAY_MODE_PARAM);
             String displayMode = displayModeText == null ? "" : displayModeText;
diff --git a/screening/source/java/ch/systemsx/cisd/openbis/dss/generic/server/AbstractTabularDataGraphServlet.java b/screening/source/java/ch/systemsx/cisd/openbis/dss/generic/server/AbstractTabularDataGraphServlet.java
index 4a85a9ea218323e52618f3cc3e3ee6e9bf529ac4..a5109e77a6dfdbcf86191ce76f353d43e5c2e657 100644
--- a/screening/source/java/ch/systemsx/cisd/openbis/dss/generic/server/AbstractTabularDataGraphServlet.java
+++ b/screening/source/java/ch/systemsx/cisd/openbis/dss/generic/server/AbstractTabularDataGraphServlet.java
@@ -76,7 +76,7 @@ public abstract class AbstractTabularDataGraphServlet extends AbstractDatasetDow
 
         public RequestParams(HttpServletRequest request)
         {
-            sessionId = getRequiredParameter(request, SESSION_ID_PARAM);
+            sessionId = getRequiredParameter(request, Utils.SESSION_ID_PARAM);
             datasetCode = getRequiredParameter(request, DATASET_CODE_PARAM);
             filePathOrNull = getOptionalParameter(request, FILE_PATH_PARAM);
             graphName = getRequiredParameter(request, GRAPH_TYPE_CODE);