diff --git a/vdirsyncer/cli/tasks.py b/vdirsyncer/cli/tasks.py
index 0feb31f..88b9f7a 100644
--- a/vdirsyncer/cli/tasks.py
+++ b/vdirsyncer/cli/tasks.py
@@ -20,9 +20,16 @@ def sync_pair(wq, pair_name, collections_to_sync, general, all_pairs,
 
     a_name, b_name, pair_options = all_pairs[pair_name]
 
+    try:
+        config_a, config_b = all_storages[a_name], all_storages[b_name]
+    except KeyError as e:
+        raise CliError('Pair {}: Storage {} not found. These are the '
+                       'configured storages: {}'
+                       .format(pair_name, str(e), list(all_storages)))
+
     all_collections = dict(collections_for_pair(
         general['status_path'], a_name, b_name, pair_name,
-        all_storages[a_name], all_storages[b_name], pair_options
+        config_a, config_b, pair_options
     ))
 
     # spawn one worker less because we can reuse the current one