diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index b27e4c1..071277c 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -354,9 +354,12 @@
   else:
     print "building image from target_files %s..." % (tree_subdir,)
     fs_config = "META/" + tree_subdir.lower() + "_filesystem_config.txt"
-    return File(name, BuildBootableImage(os.path.join(unpack_dir, tree_subdir),
-                                         os.path.join(unpack_dir, fs_config),
-                                         info_dict))
+    data = BuildBootableImage(os.path.join(unpack_dir, tree_subdir),
+                              os.path.join(unpack_dir, fs_config),
+                              info_dict))
+    if data:
+      return File(name, data)
+    return None
 
 
 def UnzipTemp(filename, pattern=None):