diff --git a/manifest_xml.py b/manifest_xml.py
index f2d04df..bf730ca 100644
--- a/manifest_xml.py
+++ b/manifest_xml.py
@@ -31,7 +31,7 @@
   urllib.parse = urlparse
 
 import gitc_utils
-from git_config import GitConfig
+from git_config import GitConfig, IsId
 from git_refs import R_HEADS, HEAD
 import platform_utils
 from project import RemoteSpec, Project, MetaProject
@@ -705,6 +705,10 @@
             p.groups.extend(groups)
           if revision:
             p.revisionExpr = revision
+            if IsId(revision):
+              p.revisionId = revision
+            else:
+              p.revisionId = None
           if remote:
             p.remote = remote.ToRemoteSpec(name)
       if node.nodeName == 'repo-hooks':