diff --git a/msi.gama.core/src/msi/gaml/expressions/operators/PrimitiveOperator.java b/msi.gama.core/src/msi/gaml/expressions/operators/PrimitiveOperator.java
index 6313a1cf5b..251769116d 100644
--- a/msi.gama.core/src/msi/gaml/expressions/operators/PrimitiveOperator.java
+++ b/msi.gama.core/src/msi/gaml/expressions/operators/PrimitiveOperator.java
@@ -215,7 +215,7 @@ public String literalValue() {
 
 	@Override
 	public IExpression resolveAgainst(final IScope scope) {
-		return new PrimitiveOperator(action, target.resolveAgainst(scope), parameters.resolveAgainst(scope),
+		return new PrimitiveOperator(action, target==null?null:target.resolveAgainst(scope), parameters==null?null:parameters.resolveAgainst(scope),
 				targetSpecies);
 	}