diff --git a/prism/src/explicit/ProbModelChecker.java b/prism/src/explicit/ProbModelChecker.java
index ede5acaf..af527b32 100644
--- a/prism/src/explicit/ProbModelChecker.java
+++ b/prism/src/explicit/ProbModelChecker.java
@@ -1037,6 +1037,11 @@ public class ProbModelChecker extends NonProbModelChecker
 	 */
 	protected StateValues checkRewardReach(Model model, Rewards modelRewards, ExpressionTemporal expr, MinMax minMax, BitSet statesOfInterest) throws PrismException
 	{
+		// No time bounds allowed
+		if (expr.hasBounds()) {
+			throw new PrismNotSupportedException("R operator cannot contain a bounded F operator: " + expr);
+		}
+		
 		// Model check the operand for all states
 		BitSet target = checkExpression(model, expr.getOperand2(), null).getBitSet();
 
diff --git a/prism/src/parser/ast/Expression.java b/prism/src/parser/ast/Expression.java
index cb770909..a0568947 100644
--- a/prism/src/parser/ast/Expression.java
+++ b/prism/src/parser/ast/Expression.java
@@ -725,10 +725,8 @@ public abstract class Expression extends ASTElement
 			{
 				public void visitPre(ExpressionTemporal e) throws PrismLangException
 				{
-					if (e.getLowerBound() != null)
-						throw new PrismLangException(e.getOperatorSymbol());
-					if (e.getUpperBound() != null)
-						throw new PrismLangException(e.getOperatorSymbol());
+					if (e.hasBounds())
+						throw new PrismLangException("");
 				}
 			});
 		} catch (PrismLangException e) {
diff --git a/prism/src/prism/NondetModelChecker.java b/prism/src/prism/NondetModelChecker.java
index e3704be7..b3a22764 100644
--- a/prism/src/prism/NondetModelChecker.java
+++ b/prism/src/prism/NondetModelChecker.java
@@ -1202,6 +1202,11 @@ public class NondetModelChecker extends NonProbModelChecker
 		JDDNode b;
 		StateValues rewards = null;
 
+		// No time bounds allowed
+		if (expr.hasBounds()) {
+			throw new PrismNotSupportedException("R operator cannot contain a bounded F operator: " + expr);
+		}
+		
 		// model check operand first
 		b = checkExpressionDD(expr.getOperand2());
 
diff --git a/prism/src/prism/ProbModelChecker.java b/prism/src/prism/ProbModelChecker.java
index cd1519e2..f2e98250 100644
--- a/prism/src/prism/ProbModelChecker.java
+++ b/prism/src/prism/ProbModelChecker.java
@@ -876,6 +876,11 @@ public class ProbModelChecker extends NonProbModelChecker
 		JDDNode b;
 		StateValues rewards = null;
 
+		// No time bounds allowed
+		if (expr.hasBounds()) {
+			throw new PrismNotSupportedException("R operator cannot contain a bounded F operator: " + expr);
+		}
+		
 		// model check operand first
 		b = checkExpressionDD(expr.getOperand2());