diff --git a/src/main/java/ch/naviqore/app/controller/RoutingController.java b/src/main/java/ch/naviqore/app/controller/RoutingController.java
index 53c960ab..e6894808 100644
--- a/src/main/java/ch/naviqore/app/controller/RoutingController.java
+++ b/src/main/java/ch/naviqore/app/controller/RoutingController.java
@@ -101,6 +101,7 @@ public List<Connection> getConnections(@RequestParam(required = false) String so
             } else if (targetStop != null) {
                 return map(service.getConnections(sourceCoordinate, targetStop, dateTime, map(timeType), config));
             } else {
+                assert sourceCoordinate != null; // never happens --> see RoutingRequestValidator.validateStopParameters
                 RoutingRequestValidator.validateCoordinates(sourceCoordinate, targetCoordinate);
                 return map(service.getConnections(sourceCoordinate, targetCoordinate, dateTime, map(timeType), config));
             }