diff --git a/Timeline/src/org/sleuthkit/autopsy/timeline/Simile2.java b/Timeline/src/org/sleuthkit/autopsy/timeline/Simile2.java
index f112e55949..422ee53d43 100644
--- a/Timeline/src/org/sleuthkit/autopsy/timeline/Simile2.java
+++ b/Timeline/src/org/sleuthkit/autopsy/timeline/Simile2.java
@@ -970,6 +970,11 @@ public class Simile2 extends CallableSystemAction implements Presenter.Toolbar,
             } else {
                 logger.log(Level.INFO, "Beginning generation of timeline");
                 
+                // if the timeline window is already open, do nothing
+                if (jf != null && jf.isVisible()) {
+                    return;
+                }
+                
                 Platform.setImplicitExit(false);
                 
                 // listen for case changes (specifically images being added).