diff --git a/Source/cmGeneratorExpressionEvaluator.cxx b/Source/cmGeneratorExpressionEvaluator.cxx
index 2e123a4d91..23f641d641 100644
--- a/Source/cmGeneratorExpressionEvaluator.cxx
+++ b/Source/cmGeneratorExpressionEvaluator.cxx
@@ -677,6 +677,23 @@ std::string GeneratorExpressionContent::Evaluate(
     }
 
   std::vector<std::string> parameters;
+  this->EvaluateParameters(node, identifier, context, dagChecker, parameters);
+  if (context->HadError)
+    {
+    return std::string();
+    }
+
+  return node->Evaluate(parameters, context, this, dagChecker);
+}
+
+//----------------------------------------------------------------------------
+std::string GeneratorExpressionContent::EvaluateParameters(
+                                const cmGeneratorExpressionNode *node,
+                                const std::string &identifier,
+                                cmGeneratorExpressionContext *context,
+                                cmGeneratorExpressionDAGChecker *dagChecker,
+                                std::vector<std::string> &parameters) const
+{
   {
   std::vector<std::vector<cmGeneratorExpressionEvaluator*> >::const_iterator
                                         pit = this->ParamChildren.begin();
@@ -732,10 +749,8 @@ std::string GeneratorExpressionContent::Evaluate(
     {
     reportError(context, this->GetOriginalExpression(), "$<" + identifier
                       + "> expression requires at least one parameter.");
-    return std::string();
     }
-
-  return node->Evaluate(parameters, context, this, dagChecker);
+  return std::string();
 }
 
 //----------------------------------------------------------------------------
diff --git a/Source/cmGeneratorExpressionEvaluator.h b/Source/cmGeneratorExpressionEvaluator.h
index 04a2acdc6b..642a02ee5d 100644
--- a/Source/cmGeneratorExpressionEvaluator.h
+++ b/Source/cmGeneratorExpressionEvaluator.h
@@ -33,6 +33,7 @@ struct cmGeneratorExpressionContext
 };
 
 struct cmGeneratorExpressionDAGChecker;
+struct cmGeneratorExpressionNode;
 
 //----------------------------------------------------------------------------
 struct cmGeneratorExpressionEvaluator
@@ -117,6 +118,13 @@ struct GeneratorExpressionContent : public cmGeneratorExpressionEvaluator
 
   ~GeneratorExpressionContent();
 
+private:
+  std::string EvaluateParameters(const cmGeneratorExpressionNode *node,
+                                 const std::string &identifier,
+                                 cmGeneratorExpressionContext *context,
+                                 cmGeneratorExpressionDAGChecker *dagChecker,
+                                 std::vector<std::string> &parameters) const;
+
 private:
   std::vector<cmGeneratorExpressionEvaluator*> IdentifierChildren;
   std::vector<std::vector<cmGeneratorExpressionEvaluator*> > ParamChildren;