diff --git a/varst/utils/parser.py b/varst/utils/parser.py
index a37926c..7933d73 100644
--- a/varst/utils/parser.py
+++ b/varst/utils/parser.py
@@ -21,7 +21,7 @@ def __init__(self) -> None:
 
         self._parser.add_argument(
             "substitutions", nargs="*",
-            help="name-value pairs of substitutions",
+            help="pairs of substitution definition. format is 'text=data'",
             type=_pattern_type,
         )
         self._parser.add_argument(