diff --git a/terminus-core/src/services/hostApp.service.ts b/terminus-core/src/services/hostApp.service.ts
index d59f3aa2..495c5d6c 100644
--- a/terminus-core/src/services/hostApp.service.ts
+++ b/terminus-core/src/services/hostApp.service.ts
@@ -106,7 +106,7 @@ export class HostAppService {
 
     toggleFullscreen () {
         let window = this.getWindow()
-        window.setFullScreen(!window.isFullScreen())
+        window.setFullScreen(!this.isFullScreen)
     }
 
     openDevTools () {