diff --git a/src/parser/ArcanistDiffParser.php b/src/parser/ArcanistDiffParser.php
index 3116570d..54a40361 100644
--- a/src/parser/ArcanistDiffParser.php
+++ b/src/parser/ArcanistDiffParser.php
@@ -116,8 +116,9 @@ final class ArcanistDiffParser {
           $root = $rinfo['URL'].'/';
         }
         $cpath = $info['Copied From URL'];
-        $cpath = substr($cpath, strlen($root));
-        if ($info['Copied From Rev']) {
+        $root_len = strlen($root);
+        if (!strncmp($cpath, $root, $root_len)) {
+          $cpath = substr($cpath, $root_len);
           // The user can "svn cp /path/to/file@12345 x", which pulls a file out
           // of version history at a specific revision. If we just use the path,
           // we'll collide with possible changes to that path in the working
@@ -129,13 +130,17 @@ final class ArcanistDiffParser {
           // TODO: In theory, you could have an '@' in your path and this could
           // cause a collision, e.g. two files named 'f' and 'f@12345'. This is
           // at least somewhat the user's fault, though.
-          if ($info['Copied From Rev'] != $info['Revision']) {
-            $cpath .= '@'.$info['Copied From Rev'];
+          if ($info['Copied From Rev']) {
+            if ($info['Copied From Rev'] != $info['Revision']) {
+              $cpath .= '@'.$info['Copied From Rev'];
+            }
           }
+          $change->setOldPath($cpath);
+          $from[$path] = $cpath;
         }
-        $change->setOldPath($cpath);
-
-        $from[$path] = $cpath;
+      } else {
+        // file was merged from another branch, treat it as a new file
+        $change->setType(ArcanistDiffChangeType::TYPE_ADD);
       }
       $type = $change->getType();
       if (($type === ArcanistDiffChangeType::TYPE_MOVE_AWAY ||