diff --git a/lib/sphinx-preview.js b/lib/sphinx-preview.js
index f1fdc5f..5348c7c 100644
--- a/lib/sphinx-preview.js
+++ b/lib/sphinx-preview.js
@@ -39,7 +39,7 @@ export default {
         this.openBrowser();
       });
     } else {
-      atom.notifications.addWarning('Active file must have reStructuredText extension (.rst)');
+      atom.notifications.addWarning('Active file must have reStructuredText extension (.rst) and must be opened as part of a Project Folder');
     }
   },
 
@@ -218,6 +218,10 @@ export default {
   },
 
   isActiveFileRst() {
+    if(!this.getCurrProjectPath()) {
+      return false;
+    }
+
     const editor = atom.workspace.getActivePaneItem();
     if (!editor || !editor.buffer) return false;
     const activeFilePath = editor.buffer.file.path;