diff --git a/src/ckeditor.js b/src/ckeditor.js
index 9a25f00..0250037 100644
--- a/src/ckeditor.js
+++ b/src/ckeditor.js
@@ -121,7 +121,9 @@ export default {
 
 		// Synchronize changes of #disabled.
 		disabled( val ) {
-			this.instance.isReadOnly = val;
+			if (this.instance) {	
+				this.instance.isReadOnly = val;
+			}
 		}
 	},