diff --git a/packages/workflow/src/Workflow.ts b/packages/workflow/src/Workflow.ts
index 816c009a1f..a3d069058d 100644
--- a/packages/workflow/src/Workflow.ts
+++ b/packages/workflow/src/Workflow.ts
@@ -906,7 +906,9 @@ export class Workflow {
 		// Execute the expression
 		try {
 			const returnValue = tmpl.tmpl(parameterValue, data);
-			if (returnValue !== null && typeof returnValue === 'object') {
+			if (typeof returnValue === 'function') {
+				throw new Error('Expression resolved to a function. Please add "()"');
+			} else if (returnValue !== null && typeof returnValue === 'object') {
 				if (returnObjectAsString === true)  {
 					return this.convertObjectValueToString(returnValue);
 				}