diff --git a/manifest_xml.py b/manifest_xml.py
index 51e653e..7d02f9d 100644
--- a/manifest_xml.py
+++ b/manifest_xml.py
@@ -183,7 +183,7 @@
     if not self._loaded:
       m = self.manifestProject
       b = m.GetBranch(m.CurrentBranch).merge
-      if b.startswith(R_HEADS):
+      if b is not None and b.startswith(R_HEADS):
         b = b[len(R_HEADS):]
       self.branch = b