diff --git a/src/mermaid.js b/src/mermaid.js
index b872df2fc..d6e67f699 100644
--- a/src/mermaid.js
+++ b/src/mermaid.js
@@ -78,7 +78,7 @@ const init = function() {
     mermaidAPI.updateSiteConfig({ gantt: mermaid.ganttConfig });
   }
 
-  const idGeneratior = utils.initIdGeneratior(conf.deterministicIds, conf.deterministicIDSeed);
+  const idGeneratior = new utils.initIdGeneratior(conf.deterministicIds, conf.deterministicIDSeed);
 
   let txt;
 
diff --git a/src/utils.js b/src/utils.js
index 97b6d125f..b6e2a9d9a 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -793,17 +793,19 @@ export const configureSvgSize = function(svgElem, height, width, useMaxWidth) {
   d3Attrs(svgElem, attrs);
 };
 
-export const initIdGeneratior = function(deterministic, seed) {
-  if (!deterministic) return { next: () => Date.now() };
-  class iterator {
-    constructor() {
-      return (this.count = seed ? seed.length : 0);
-    }
-    next() {
-      return this.count++;
-    }
+export const initIdGeneratior = class iterator {
+  constructor (deterministic, seed) {
+    this.deterministic = deterministic;
+    this.seed = seed;
+
+    this.count = seed ? seed.length : 0
+  }
+
+  next() {
+    if (!this.deterministic) return Date.now();
+
+    return this.count++;
   }
-  return new iterator();
 };
 
 export default {
diff --git a/src/utils.spec.js b/src/utils.spec.js
index 66b13a276..c490099dd 100644
--- a/src/utils.spec.js
+++ b/src/utils.spec.js
@@ -256,7 +256,7 @@ describe('when calculating SVG size', function() {
 
 describe('when initializing the id generator', function () {
   it('should return a random number generator based on Date', function (done) {
-    const idGenerator = utils.initIdGeneratior(false)
+    const idGenerator = new utils.initIdGeneratior(false)
     expect(typeof idGenerator.next).toEqual('function')
     const lastId = idGenerator.next()
     setTimeout(() => {
@@ -266,7 +266,7 @@ describe('when initializing the id generator', function () {
   });
 
   it('should return a non random number generator', function () {
-    const idGenerator = utils.initIdGeneratior(true)
+    const idGenerator = new utils.initIdGeneratior(true)
     expect(typeof idGenerator.next).toEqual('function')
     const start = 0
     const lastId = idGenerator.next()
@@ -275,7 +275,7 @@ describe('when initializing the id generator', function () {
   });
 
   it('should return a non random number generator based on seed', function () {
-    const idGenerator = utils.initIdGeneratior(true, 'thisIsASeed')
+    const idGenerator = new utils.initIdGeneratior(true, 'thisIsASeed')
     expect(typeof idGenerator.next).toEqual('function')
     const start = 11
     const lastId = idGenerator.next()