diff --git a/src/applications/pholio/controller/PholioInlineController.php b/src/applications/pholio/controller/PholioInlineController.php
--- a/src/applications/pholio/controller/PholioInlineController.php
+++ b/src/applications/pholio/controller/PholioInlineController.php
@@ -112,6 +112,8 @@
       } else if ($inline->getID()) {
         $inline->delete();
         $dictionary = array();
+      } else {
+          throw new Exception(pht('Comment cannot be empty.'));
       }
 
       return id(new AphrontAjaxResponse())->setContent($dictionary);