diff --git a/src/mermaid.js b/src/mermaid.js
index 64016e26a..94fec80fc 100644
--- a/src/mermaid.js
+++ b/src/mermaid.js
@@ -78,7 +78,7 @@ const init = function() {
     mermaidAPI.updateSiteConfig({ gantt: mermaid.ganttConfig });
   }
 
-  const nextId = utils.initIdGeneratior(conf.deterministicIds, conf.deterministicIDSeed);
+  const nextId = utils.initIdGeneratior(conf.deterministicIds, conf.deterministicIDSeed).next;
 
   let txt;
 
diff --git a/src/utils.js b/src/utils.js
index 471fddd44..18e35f738 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -791,12 +791,16 @@ export const configureSvgSize = function(svgElem, height, width, useMaxWidth) {
 };
 
 export const initIdGeneratior = function(deterministic, seed) {
-  if (!deterministic) return () => Date.now();
-  const iterator = function() {
-    return this.count++;
-  };
-  iterator.seed = seed ? seed.length : 0;
-  return iterator;
+  if (!deterministic) return { next: () => Date.now() };
+  class iterator {
+    constructor() {
+      return (this.count = seed ? seed.length : 0);
+    }
+    next() {
+      return this.count++;
+    }
+  }
+  return new iterator();
 };
 
 export default {
@@ -820,5 +824,6 @@ export default {
   generateId,
   random,
   memoize,
-  runFunc
+  runFunc,
+  initIdGeneratior
 };
diff --git a/src/utils.spec.js b/src/utils.spec.js
index 756ad3794..66b13a276 100644
--- a/src/utils.spec.js
+++ b/src/utils.spec.js
@@ -253,3 +253,34 @@ describe('when calculating SVG size', function() {
     expect(attrs.get('width')).toEqual(200);
   });
 });
+
+describe('when initializing the id generator', function () {
+  it('should return a random number generator based on Date', function (done) {
+    const idGenerator = utils.initIdGeneratior(false)
+    expect(typeof idGenerator.next).toEqual('function')
+    const lastId = idGenerator.next()
+    setTimeout(() => {
+      expect(idGenerator.next() > lastId).toBe(true)
+      done()
+    }, 5)
+  });
+
+  it('should return a non random number generator', function () {
+    const idGenerator = utils.initIdGeneratior(true)
+    expect(typeof idGenerator.next).toEqual('function')
+    const start = 0
+    const lastId = idGenerator.next()
+    expect(start).toEqual(lastId)
+    expect(idGenerator.next()).toEqual(lastId +1)
+  });
+
+  it('should return a non random number generator based on seed', function () {
+    const idGenerator = utils.initIdGeneratior(true, 'thisIsASeed')
+    expect(typeof idGenerator.next).toEqual('function')
+    const start = 11
+    const lastId = idGenerator.next()
+    expect(start).toEqual(lastId)
+    expect(idGenerator.next()).toEqual(lastId +1)
+  });
+
+})