diff --git a/src/main/java/crml/compiler/OperatorMapping.java b/src/main/java/crml/compiler/OperatorMapping.java
index 5fa3db5..f8fc0ff 100644
--- a/src/main/java/crml/compiler/OperatorMapping.java
+++ b/src/main/java/crml/compiler/OperatorMapping.java
@@ -241,7 +241,8 @@ public static HashMap<String, List<Signature>> get_operator_map (){
 		// and operators	
 		List<Signature> and_sigs = 
 						Arrays.asList(new Signature("CRMLtoModelica.Functions.and4", bool2, params, "Boolean", Type.FUNCTION),
-								new Signature("arrayAnd", bool1, params, "Boolean", Type.SET_OP, setUnary, false));
+								new Signature("arrayAnd", bool1, params, "Boolean", Type.SET_OP, setUnary, false),
+								new Signature("unaryBoolAnd", bool1, params, "Boolean", Type.FUNCTION));
 		built_in_operators.put("and", and_sigs);
 		
 		// or operators	
diff --git a/src/test/resources/testModels/libraries/ETL_test/old_EnsureAtEnd.crml b/src/test/resources/testModels/libraries/ETL_test/old_EnsureAtEnd.crml
index 8819e39..ad9a234 100644
--- a/src/test/resources/testModels/libraries/ETL_test/old_EnsureAtEnd.crml
+++ b/src/test/resources/testModels/libraries/ETL_test/old_EnsureAtEnd.crml
@@ -1,11 +1,12 @@
 model EnsureAtEnd is ETL union {
 
-	// Requirement
-	Boolean y is 'check' u 'at end of' {timePeriod};
 	
 	// Operator for checking that a requirement is satisfied at the end of a time period
 	Operator [ Boolean ] 'check' Boolean b 'at end of' Periods P = 'check' varying1 'id' b 'over' P;
 	
+	// Requirement
+	Boolean y is 'check' u 'at end of' {timePeriod};
+	
 	// Inputs
 	Event e1 is external;
 	Event e2 is external;