diff --git a/chainsyncer/cli/arg.py b/chainsyncer/cli/arg.py
index d3e680a..3884b25 100644
--- a/chainsyncer/cli/arg.py
+++ b/chainsyncer/cli/arg.py
@@ -7,6 +7,7 @@ def process_flags(argparser, flags):
     if flags & SyncFlag.RANGE > 0:
         argparser.add_argument('--offset', type=int, help='Block to start sync from. Default is start of history (0).')
         argparser.add_argument('--until', type=int, default=-1, help='Block to stop sync on. Default is stop at block height of first run.')
+        argparser.add_argument('--single', action='store_true', help='Execute a single sync, regardless of previous states')
     if flags & SyncFlag.HEAD > 0:
         argparser.add_argument('--head', action='store_true', help='Start from latest block as offset')
         argparser.add_argument('--keep-alive', action='store_true', help='Do not stop syncing when caught up')
diff --git a/chainsyncer/cli/config.py b/chainsyncer/cli/config.py
index 266161b..d840512 100644
--- a/chainsyncer/cli/config.py
+++ b/chainsyncer/cli/config.py
@@ -17,4 +17,6 @@ def process_config(config, args, flags):
             config.add(getattr(args, 'keep_alive'), '_KEEP_ALIVE')
             config.add(getattr(args, 'head'), '_HEAD')
 
+        config.add(getattr(args, 'single'), '_SINGLE')
+
         return config