diff --git a/CHANGELOG.md b/CHANGELOG.md
index a8ff8958..92e34fbd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,8 @@
 Changelog
 All notable changes to ngx-gantt will be documented in this file.
 
+### [0.0.20](https://github.com/worktile/ngx-gantt/compare/0.0.18...0.0.20) (2020-07-03)
+
 ### [0.0.19](https://github.com/worktile/ngx-gantt/compare/0.0.18...0.0.19) (2020-07-02)
 
 ### [0.0.18](https://github.com/worktile/ngx-gantt/compare/0.0.17...0.0.18) (2020-06-30)
diff --git a/package-lock.json b/package-lock.json
index 7f2a0cc5..39565e13 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "@worktile/gantt",
-  "version": "0.0.19",
+  "version": "0.0.20",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index 4372459b..a1365f73 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@worktile/gantt",
-  "version": "0.0.19",
+  "version": "0.0.20",
   "description": "A modern and powerful gantt chart component for Angular",
   "keywords": [
     "gantt",
diff --git a/packages/gantt/package.json b/packages/gantt/package.json
index 7bd96aa2..b6cdb462 100644
--- a/packages/gantt/package.json
+++ b/packages/gantt/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@worktile/gantt",
-  "version": "0.0.19",
+  "version": "0.0.20",
   "peerDependencies": {
     "@angular/common": "^8.2.14",
     "@angular/core": "^8.2.14"
diff --git a/packages/gantt/src/gantt-upper.ts b/packages/gantt/src/gantt-upper.ts
index b2874534..1c372a62 100644
--- a/packages/gantt/src/gantt-upper.ts
+++ b/packages/gantt/src/gantt-upper.ts
@@ -217,8 +217,12 @@ export abstract class GanttUpper {
         let start = this.start;
         let end = this.end;
         this.originItems.forEach((item) => {
-            start = start ? Math.min(start, item.start) : item.start;
-            end = end ? Math.max(end, item.end) : item.end;
+            if (item.start) {
+                start = start ? Math.min(start, item.start) : item.start;
+            }
+            if (item.end) {
+                end = end ? Math.max(end, item.end) : item.end;
+            }
         });
         return {
             start: new GanttDate(start),