diff --git a/contribs/parking/src/main/java/org/matsim/contrib/parking/parkingproxy/CarEgressWalkChanger.java b/contribs/parking/src/main/java/org/matsim/contrib/parking/parkingproxy/CarEgressWalkChanger.java
index ee2a32a759e..b78bd899b78 100644
--- a/contribs/parking/src/main/java/org/matsim/contrib/parking/parkingproxy/CarEgressWalkChanger.java
+++ b/contribs/parking/src/main/java/org/matsim/contrib/parking/parkingproxy/CarEgressWalkChanger.java
@@ -122,9 +122,11 @@ private void changeEgressTimesByGridcell(Collection<? extends Person> population
 		for (Person p : population) {
 			for (LegActPair walkActPair : this.egressFinder.findEgressWalks(p.getSelectedPlan())) {
 				if (reverse) {
-					double penalty = (double) walkActPair.leg.getAttributes().getAttribute(PENALTY_ATTRIBUTE);
-					setTimes(walkActPair, -penalty);
-					walkActPair.leg.getAttributes().removeAttribute(PENALTY_ATTRIBUTE);
+					Object readPenalty = walkActPair.leg.getAttributes().getAttribute(PENALTY_ATTRIBUTE);
+					if (readPenalty != null) {
+						setTimes(walkActPair, - (double) readPenalty);
+						walkActPair.leg.getAttributes().removeAttribute(PENALTY_ATTRIBUTE);
+					}
 				} else {
 					double penalty = Math.round(this.observer.getPenaltyCalculator().getPenalty(walkActPair.leg.getDepartureTime().seconds(), walkActPair.act.getCoord()));
 					setTimes(walkActPair, penalty);