diff --git a/prism/src/explicit/ProbModelChecker.java b/prism/src/explicit/ProbModelChecker.java
index 2ebbda98..4ee70c92 100644
--- a/prism/src/explicit/ProbModelChecker.java
+++ b/prism/src/explicit/ProbModelChecker.java
@@ -1034,7 +1034,7 @@ public class ProbModelChecker extends NonProbModelChecker
 		if (Expression.isReach(expr)) {
 			return checkRewardReach(model, modelRewards, (ExpressionTemporal) expr, minMax, statesOfInterest);
 		}
-		else if (Expression.isCoSafeLTLSyntactic(expr)) {
+		else if (Expression.isCoSafeLTLSyntactic(expr, true)) {
 			return checkRewardCoSafeLTL(model, modelRewards, expr, minMax, statesOfInterest);
 		}
 		throw new PrismException("R operator contains a path formula that is not syntactically co-safe: " + expr);