diff --git a/src/applications/diffusion/document/DiffusionDocumentRenderingEngine.php b/src/applications/diffusion/document/DiffusionDocumentRenderingEngine.php
--- a/src/applications/diffusion/document/DiffusionDocumentRenderingEngine.php
+++ b/src/applications/diffusion/document/DiffusionDocumentRenderingEngine.php
@@ -87,7 +87,7 @@
     $ref->setSymbolMetadata($this->getSymbolMetadata());
 
     $coverage = $drequest->loadCoverage();
-    if (strlen($coverage)) {
+    if (phutil_nonempty_string($coverage)) {
       $ref->addCoverage($coverage);
     }
   }