diff --git a/gitiles-servlet/src/main/java/com/google/gitiles/HtmlDiffFormatter.java b/gitiles-servlet/src/main/java/com/google/gitiles/HtmlDiffFormatter.java
index 63b1eb8..993197d 100644
--- a/gitiles-servlet/src/main/java/com/google/gitiles/HtmlDiffFormatter.java
+++ b/gitiles-servlet/src/main/java/com/google/gitiles/HtmlDiffFormatter.java
@@ -122,6 +122,7 @@
         out.write(LINE_CHANGE_BEGIN);
         break;
     }
+    out.write(prefix);
     out.write(StringEscapeUtils.escapeHtml4(text.getString(cur)).getBytes(Charsets.UTF_8));
     out.write(LINE_END);
   }