diff --git a/app/components/SimpleEditor/elements/note/NoteTool.js b/app/components/SimpleEditor/elements/note/NoteTool.js
index c66a6e4e404f73e2673b6e3518c3f86ebbb1c50b..ab792f138d6e27f91614b73b21352a74ff1db22a 100644
--- a/app/components/SimpleEditor/elements/note/NoteTool.js
+++ b/app/components/SimpleEditor/elements/note/NoteTool.js
@@ -1,4 +1,3 @@
-import { isUndefined } from 'lodash'
 import { AnnotationTool } from 'substance'
 
 class NoteTool extends AnnotationTool {
@@ -6,7 +5,7 @@ class NoteTool extends AnnotationTool {
     const el = super.renderButton($$)
     const readOnly = this.isSurfaceReadOnly()
 
-    if (!isUndefined(readOnly)) el.attr('disabled', 'true')
+    if (readOnly === true) el.attr('disabled', 'true')
     return el
   }