diff --git a/src/applications/project/remarkup/ProjectRemarkupRule.php b/src/applications/project/remarkup/ProjectRemarkupRule.php
--- a/src/applications/project/remarkup/ProjectRemarkupRule.php
+++ b/src/applications/project/remarkup/ProjectRemarkupRule.php
@@ -20,17 +20,13 @@
   }
 
   protected function getObjectIDPattern() {
-    // NOTE: This explicitly does not match strings which contain only
-    // digits, because digit strings like "#123" are used to reference tasks at
-    // Facebook and are somewhat conventional in general.
-
-    // The latter half of this rule matches monograms with internal periods,
-    // like `#domain.com`, but does not match monograms with terminal periods,
-    // because they're probably just puncutation.
+    // NOTE: The latter half of this rule matches monograms with internal
+    // periods, like `#domain.com`, but does not match monograms with terminal
+    // periods, because they're probably just puncutation.
 
     // Broadly, this will not match every possible project monogram, and we
-    // accept some false negatives -- like `#1` or `#dot.` -- in order to avoid
-    // a bunch of false positives on general use of the `#` character.
+    // accept some false negatives -- like `#dot.` -- in order to avoid a bunch
+    // of false positives on general use of the `#` character.
 
     // In other contexts, the PhabricatorProjectProjectPHIDType pattern is
     // controlling and these names should parse correctly.
@@ -38,17 +34,14 @@
     // These characters may never appear anywhere in a hashtag.
     $never = '\s?!,:;{}#\\(\\)"\'';
 
-    // These characters may not appear at the beginning.
-    $never_first = '.\d';
-
-    // These characters may not appear at the end.
-    $never_last = '.';
+    // These characters may not appear at the edge of the string.
+    $never_edge = '.';
 
     return
-      '[^'.$never_first.$never.']+'.
+      '[^'.$never_edge.$never.']+'.
       '(?:'.
         '[^'.$never.']*'.
-        '[^'.$never_last.$never.']+'.
+        '[^'.$never_edge.$never.']+'.
       ')*';
   }
 
diff --git a/src/applications/project/remarkup/__tests__/ProjectRemarkupRuleTestCase.php b/src/applications/project/remarkup/__tests__/ProjectRemarkupRuleTestCase.php
--- a/src/applications/project/remarkup/__tests__/ProjectRemarkupRuleTestCase.php
+++ b/src/applications/project/remarkup/__tests__/ProjectRemarkupRuleTestCase.php
@@ -33,7 +33,21 @@
       ),
       '#123' => array(
         'embed' => array(),
-        'ref' => array(),
+        'ref' => array(
+          array(
+            'offset' => 1,
+            'id' => '123',
+          ),
+        ),
+      ),
+      '#2x4' => array(
+        'embed' => array(),
+        'ref' => array(
+          array(
+            'offset' => 1,
+            'id' => '2x4',
+          ),
+        ),
       ),
       '#security#123' => array(
         'embed' => array(),