diff --git a/src/event.ts b/src/event.ts
index 543fba9d..b058b365 100755
--- a/src/event.ts
+++ b/src/event.ts
@@ -1816,9 +1816,12 @@ export default class ICalEvent {
             if (this.data.organizer.email && this.data.organizer.mailto) {
                 g += ';EMAIL=' + escape(this.data.organizer.email, false);
             }
+
+            g += ':';
             if(this.data.organizer.email) {
-                g += ':mailto:' + escape(this.data.organizer.mailto || this.data.organizer.email, false);
+                g += 'mailto:' + escape(this.data.organizer.mailto || this.data.organizer.email, false);
             }
+
             g += '\r\n';
         }
 
diff --git a/test/event.ts b/test/event.ts
index 82108887..9cae0528 100644
--- a/test/event.ts
+++ b/test/event.ts
@@ -1432,6 +1432,16 @@ describe('ical-generator Event', function () {
                 sentBy: undefined
             });
         });
+
+        it('should include a : (PR #610)', function () {
+            const event = new ICalEvent({
+                start: moment(),
+                summary: 'Example Event',
+                organizer: { name: 'Some Guy' }
+            }, new ICalCalendar());
+
+            assert.ok(event.toString().includes('ORGANIZER;CN="Some Guy":'));
+        });
     });
 
     describe('createAttendee()', function () {