diff --git a/src/utils/PhutilProseDifferenceEngine.php b/src/utils/PhutilProseDifferenceEngine.php
index e653eab..ee9e168 100644
--- a/src/utils/PhutilProseDifferenceEngine.php
+++ b/src/utils/PhutilProseDifferenceEngine.php
@@ -1,92 +1,98 @@
 <?php
 
 final class PhutilProseDifferenceEngine extends Phobject {
 
   public function getDiff($u, $v) {
     $diff = id(new PhutilProseDiff());
 
     $this->buildDiff($diff, $u, $v, 1);
     $diff->reorderParts();
 
     return $diff;
   }
 
   private function buildDiff(PhutilProseDiff $diff, $u, $v, $level) {
     if ($level == 4) {
       $diff->addPart('-', $u);
       $diff->addPart('+', $v);
       return;
     }
 
     $u_parts = $this->splitCorpus($u, $level);
     $v_parts = $this->splitCorpus($v, $level);
 
     $matrix = id(new PhutilEditDistanceMatrix())
       ->setSequences($u_parts, $v_parts)
       ->setComputeString(true);
 
     $u_pos = 0;
     $v_pos = 0;
 
     $edits = $matrix->getEditString();
     $edits_length = strlen($edits);
 
     for ($ii = 0; $ii < $edits_length; $ii++) {
       $c = $edits[$ii];
       if ($c == 's') {
         $diff->addPart('=', $u_parts[$u_pos]);
         $u_pos++;
         $v_pos++;
       } else if ($c == 'd') {
         $diff->addPart('-', $u_parts[$u_pos]);
         $u_pos++;
       } else if ($c == 'i') {
         $diff->addPart('+', $v_parts[$v_pos]);
         $v_pos++;
       } else if ($c == 'x') {
         $this->buildDiff($diff, $u_parts[$u_pos], $v_parts[$v_pos], $level + 1);
         $u_pos++;
         $v_pos++;
       } else {
         throw new Exception(
           pht(
             'Unexpected character ("%s") in edit string.',
             $c));
       }
     }
   }
 
   private function splitCorpus($corpus, $level) {
     switch ($level) {
       case 1:
         // Level 1: Split into sentences.
         $expr = '/([\n,!;?\.]+)/';
         break;
       case 2:
         // Level 2: Split into words.
         $expr = '/(\s+)/';
         break;
       case 3:
         // Level 3: Split into characters.
         return phutil_utf8v_combined($corpus);
     }
 
     $pieces = preg_split($expr, $corpus, -1, PREG_SPLIT_DELIM_CAPTURE);
     return $this->stitchPieces($pieces);
   }
 
   private function stitchPieces(array $pieces) {
     $results = array();
     $count = count($pieces);
     for ($ii = 0; $ii < $count; $ii += 2) {
       $result = $pieces[$ii];
       if ($ii + 1 < $count) {
         $result .= $pieces[$ii + 1];
       }
       $results[] = $result;
     }
 
+    // If the input ended with a delimiter, we can get an empty final piece.
+    // Just discard it.
+    if (last($results) == '') {
+      array_pop($results);
+    }
+
     return $results;
   }
 
 }