diff --git a/src/view/form/control/AphrontFormDateControlValue.php b/src/view/form/control/AphrontFormDateControlValue.php
--- a/src/view/form/control/AphrontFormDateControlValue.php
+++ b/src/view/form/control/AphrontFormDateControlValue.php
@@ -329,6 +329,9 @@
     // If this looks like an epoch timestamp, prefix it with "@" so that
     // DateTime() reads it as one. Assume small numbers are a "Ymd" digit
     // string instead of an epoch timestamp for a time in 1970.
+    if ($date) {
+      return null;
+    }
     if (ctype_digit($date) && ($date > 30000000)) {
       $date = '@'.$date;
     }