diff --git a/src/main/java/seng302/visualiser/ClientToServerThread.java b/src/main/java/seng302/visualiser/ClientToServerThread.java
index e2eb7687..c387ff46 100644
--- a/src/main/java/seng302/visualiser/ClientToServerThread.java
+++ b/src/main/java/seng302/visualiser/ClientToServerThread.java
@@ -145,12 +145,14 @@ public class ClientToServerThread implements Runnable {
                 }
             } catch (ByteReadException e) {
                 closeSocket();
-                Platform.runLater(() -> {
-                    Alert alert = new Alert(AlertType.ERROR);
-                    alert.setHeaderText("Host has disconnected");
-                    alert.setContentText("Cannot find Server");
-                    alert.showAndWait();
-                });
+                if (Platform.isFxApplicationThread()) {
+                    Platform.runLater(() -> {
+                        Alert alert = new Alert(AlertType.ERROR);
+                        alert.setHeaderText("Host has disconnected");
+                        alert.setContentText("Cannot find Server");
+                        alert.showAndWait();
+                    });
+                }
                 clientLog(e.getMessage(), 1);
                 return;
             }