diff --git a/core/modules/widgets/action-setfield.js b/core/modules/widgets/action-setfield.js
index 1e1ba6d8e..98079f00c 100644
--- a/core/modules/widgets/action-setfield.js
+++ b/core/modules/widgets/action-setfield.js
@@ -61,7 +61,9 @@ SetFieldWidget.prototype.invokeAction = function(triggeringWidget,event) {
 	var self = this,
 		options = {};
 	options.suppressTimestamp = !this.actionTimestamp;
-	this.wiki.setText(this.actionTiddler,this.actionField,this.actionIndex,this.actionValue,options);
+	if((typeof this.actionField == "string") || (typeof this.actionIndex == "string")  || (typeof this.actionValue == "string")) {
+		this.wiki.setText(this.actionTiddler,this.actionField,this.actionIndex,this.actionValue,options);
+	}
 	$tw.utils.each(this.attributes,function(attribute,name) {
 		if(name.charAt(0) !== "$") {
 			self.wiki.setText(self.actionTiddler,name,undefined,attribute,options);