diff --git a/gitc_utils.py b/gitc_utils.py
index a388dc2..7a35e7a 100644
--- a/gitc_utils.py
+++ b/gitc_utils.py
@@ -24,6 +24,8 @@
 import git_config
 import wrapper
 
+from error import ManifestParseError
+
 NUM_BATCH_RETRIEVE_REVISIONID = 300
 
 def get_gitc_manifest_dir():
@@ -54,7 +56,11 @@
     if gitcmd.Wait():
       print('FATAL: Failed to retrieve revisionExpr for %s' % proj)
       sys.exit(1)
-    proj.revisionExpr = gitcmd.stdout.split('\t')[0]
+    revisionExpr = gitcmd.stdout.split('\t')[0]
+    if not revisionExpr:
+      raise(ManifestParseError('Invalid SHA-1 revision project %s (%s)' %
+                               (proj.remote.url, proj.revisionExpr)))
+    proj.revisionExpr = revisionExpr
 
 def _manifest_groups(manifest):
   """Returns the manifest group string that should be synced