diff --git a/rl_coach/filters/README.md b/rl_coach/filters/README.md
index 9ecc817..aa781c3 100644
--- a/rl_coach/filters/README.md
+++ b/rl_coach/filters/README.md
@@ -20,7 +20,7 @@ or for reward filters:
 ```bash
 from coach.filters.filter import RewardFilter
 
-class CustomFilter(ObservationFilter):
+class CustomFilter(RewardFilter):
   def __init__(self):
     ...
   def filter(self, env_response: EnvResponse) -> EnvResponse:
@@ -67,4 +67,4 @@ input_filter = InputFilter(
 
 result = input_filter.filter(env_response)
 
-```
\ No newline at end of file
+```