diff --git a/git-filter-repo b/git-filter-repo
index ed339dc..3363cca 100755
--- a/git-filter-repo
+++ b/git-filter-repo
@@ -1109,7 +1109,9 @@ def get_args():
                       help='''Do not change the repository.  Run `git
                               fast-export` and filter its output, and save
                               both the original and the filtered version for
-                              comparison.''')
+                              comparison.  Some filtering of empty commits
+                              may not occur due to inability to query the
+                              fast-import backend.''')
   parser.add_argument('--debug', action='store_true',
                       help='''Print additional information about operations
                               being performed and commands being run.  When