diff --git a/src/parser/ArcanistDiffParser.php b/src/parser/ArcanistDiffParser.php
index ad0e00e5..4ddf5284 100644
--- a/src/parser/ArcanistDiffParser.php
+++ b/src/parser/ArcanistDiffParser.php
@@ -188,12 +188,12 @@ final class ArcanistDiffParser {
   }
 
   public function parseDiff($diff) {
-    $this->didStartParse($diff);
-
-    if ($this->getLine() === null) {
-      $this->didFailParse("Can't parse an empty diff!");
+    if (!strlen(trim($diff))) {
+      throw new Exception("Can't parse an empty diff!");
     }
 
+    $this->didStartParse($diff);
+
     do {
       $patterns = array(
         // This is a normal SVN text change, probably from "svn diff".