diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -454,6 +454,7 @@
     'DiffusionCommitQuery' => 'applications/diffusion/query/DiffusionCommitQuery.php',
     'DiffusionCommitRef' => 'applications/diffusion/data/DiffusionCommitRef.php',
     'DiffusionCommitRemarkupRule' => 'applications/diffusion/remarkup/DiffusionCommitRemarkupRule.php',
+    'DiffusionCommitRemarkupRuleTestCase' => 'applications/diffusion/remarkup/__tests__/DiffusionCommitRemarkupRuleTestCase.php',
     'DiffusionCommitTagsController' => 'applications/diffusion/controller/DiffusionCommitTagsController.php',
     'DiffusionConduitAPIMethod' => 'applications/diffusion/conduit/DiffusionConduitAPIMethod.php',
     'DiffusionController' => 'applications/diffusion/controller/DiffusionController.php',
@@ -3458,6 +3459,7 @@
     'DiffusionCommitQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
     'DiffusionCommitRef' => 'Phobject',
     'DiffusionCommitRemarkupRule' => 'PhabricatorObjectRemarkupRule',
+    'DiffusionCommitRemarkupRuleTestCase' => 'PhabricatorTestCase',
     'DiffusionCommitTagsController' => 'DiffusionController',
     'DiffusionConduitAPIMethod' => 'ConduitAPIMethod',
     'DiffusionController' => 'PhabricatorController',
diff --git a/src/applications/diffusion/remarkup/__tests__/DiffusionCommitRemarkupRuleTestCase.php b/src/applications/diffusion/remarkup/__tests__/DiffusionCommitRemarkupRuleTestCase.php
new file mode 100644
--- /dev/null
+++ b/src/applications/diffusion/remarkup/__tests__/DiffusionCommitRemarkupRuleTestCase.php
@@ -0,0 +1,60 @@
+<?php
+
+final class DiffusionCommitRemarkupRuleTestCase extends PhabricatorTestCase {
+
+  public function testProjectObjectRemarkup() {
+    $cases = array(
+      '{rP12f3f6d3a9ef9c7731051815846810cb3c4cd248}' => array(
+        'embed' => array(
+          array(
+            'offset' => 1,
+            'id' => 'rP12f3f6d3a9ef9c7731051815846810cb3c4cd248',
+          ),
+        ),
+        'ref' => array(
+          array(
+            'offset' => 1,
+            'id' => 'rP12f3f6d3a9ef9c7731051815846810cb3c4cd248',
+          ),
+        ),
+      ),
+      '{rP1234, key=value}' => array(
+        'embed' => array(
+          array(
+            'offset' => 1,
+            'id' => 'rP1234',
+            'tail' => ', key=value',
+          ),
+        ),
+        'ref' => array(
+          array(
+            'offset' => 1,
+            'id' => 'rP1234',
+          ),
+        ),
+      ),
+      '{rP1234 key=value}' => array(
+        'embed' => array(
+          array(
+            'offset' => 1,
+            'id' => 'rP1234',
+            'tail' => ' key=value',
+          ),
+        ),
+        'ref' => array(
+          array(
+            'offset' => 1,
+            'id' => 'rP1234',
+          ),
+        ),
+      ),
+    );
+
+    foreach ($cases as $input => $expect) {
+      $rule = new DiffusionCommitRemarkupRule();
+      $matches = $rule->extractReferences($input);
+      $this->assertEqual($expect, $matches, $input);
+    }
+  }
+
+}
diff --git a/src/infrastructure/markup/rule/PhabricatorObjectRemarkupRule.php b/src/infrastructure/markup/rule/PhabricatorObjectRemarkupRule.php
--- a/src/infrastructure/markup/rule/PhabricatorObjectRemarkupRule.php
+++ b/src/infrastructure/markup/rule/PhabricatorObjectRemarkupRule.php
@@ -166,7 +166,7 @@
     $prefix = preg_quote($prefix);
     $id = $this->getObjectIDPattern();
 
-    return '(\B{'.$prefix.'('.$id.')((?:[^}\\\\]|\\\\.)*)}\B)u';
+    return '(\B{'.$prefix.'('.$id.')([,\s](?:[^}\\\\]|\\\\.)*)?}\B)u';
   }
 
   private function getObjectReferencePattern() {