diff --git a/core/modules/parsers/wikiparser/rules/functiondef.js b/core/modules/parsers/wikiparser/rules/functiondef.js
index 665b939f2..9e748ef48 100644
--- a/core/modules/parsers/wikiparser/rules/functiondef.js
+++ b/core/modules/parsers/wikiparser/rules/functiondef.js
@@ -27,7 +27,7 @@ Instantiate parse rule
 exports.init = function(parser) {
 	this.parser = parser;
 	// Regexp to match
-	this.matchRegExp = /^\\function\s+([^(\s]+)\(\s*([^)]*)\)(\s*\r?\n)?/mg;
+	this.matchRegExp = /^\\function\s+([^(\s]+)(\(\s*([^)]*)\))?(\s*\r?\n)?/mg;
 };
 
 /*
@@ -37,9 +37,9 @@ exports.parse = function() {
 	// Move past the macro name and parameters
 	this.parser.pos = this.matchRegExp.lastIndex;
 	// Parse the parameters
-	var paramString = this.match[2],
+	var paramString = this.match[3],
 		params = [];
-	if(paramString !== "") {
+	if(this.match[2]) {
 		var reParam = /\s*([A-Za-z0-9\-_]+)(?:\s*:\s*(?:"""([\s\S]*?)"""|"([^"]*)"|'([^']*)'|([^"'\s]+)))?/mg,
 			paramMatch = reParam.exec(paramString);
 		while(paramMatch) {
@@ -56,7 +56,7 @@ exports.parse = function() {
 	}
 	// Is this a multiline definition?
 	var reEnd;
-	if(this.match[3]) {
+	if(this.match[4]) {
 		// If so, the end of the body is marked with \end
 		reEnd = /(\r?\n\\end[^\S\n\r]*(?:$|\r?\n))/mg;
 	} else {
diff --git a/editions/test/tiddlers/tests/test-wikitext-parser.js b/editions/test/tiddlers/tests/test-wikitext-parser.js
index 7daf3e76f..6c3d15ac6 100644
--- a/editions/test/tiddlers/tests/test-wikitext-parser.js
+++ b/editions/test/tiddlers/tests/test-wikitext-parser.js
@@ -119,7 +119,23 @@ describe("WikiText parser tests", function() {
 		);
 	});
 
-	it("should parse function definitions", function() {
+	it("should parse function definitions with no parameters", function() {
+		expect(parse("\\function myMacro\nnothing\n\\end\n")).toEqual(
+
+			[ { type : 'set', attributes : { name : { type : 'string', value : 'myMacro' }, value : { type : 'string', value : 'nothing' } }, children : [  ], variableParams : [  ], isFunctionDefinition : true } ]
+
+		);
+	});
+
+	it("should parse single line function definitions with no parameters", function() {
+		expect(parse("\\function myMacro nothing\n")).toEqual(
+
+			[ { type : 'set', attributes : { name : { type : 'string', value : 'myMacro' }, value : { type : 'string', value : 'nothing' } }, children : [  ], variableParams : [  ], isFunctionDefinition : true } ]
+
+		);
+	});
+
+	it("should parse function definitions with parameters", function() {
 		expect(parse("\\function myMacro(one,two,three,four:elephant)\nnothing\n\\end\n")).toEqual(
 
 			[ { type : 'set', attributes : { name : { type : 'string', value : 'myMacro' }, value : { type : 'string', value : 'nothing' } }, children : [  ], variableParams : [ { name: 'one' }, { name: 'two' }, { name: 'three' }, { name: 'four', default: 'elephant' } ], isFunctionDefinition : true } ]