diff --git a/markdownx/fields.py b/markdownx/fields.py
index 0252655..b27993d 100644
--- a/markdownx/fields.py
+++ b/markdownx/fields.py
@@ -11,5 +11,5 @@ class MarkdownxFormField(forms.CharField):
     def __init__(self, *args, **kwargs):
         super(MarkdownxFormField, self).__init__(*args, **kwargs)
 
-        if self.widget.__class__ != AdminMarkdownxWidget:
+        if not issubclass(self.widget.__class__, MarkdownxWidget):
             self.widget = MarkdownxWidget()