diff --git a/changelog.md b/changelog.md
index 5b582d99a369e78c7ebf70fce47bb4a5152e1444..7232dba6c1ded713e7dcc09c4c191846a332aa9d 100644
--- a/changelog.md
+++ b/changelog.md
@@ -10,7 +10,7 @@ Changes since Flatland 2.0.0
 - agent attribute `next_malfunction`is not used anymore, it will be removed fully in future versions.
 - `break_agent()` function is introduced which induces malfunctions in agent according to poisson process
 - `_fix_agent_after_malfunction()` fixes agents after attribute `malfunction == 0`
-- Intoduced the concept of malfunction generators. Here you can add different malfunction models in future updates. Currently it only loads from files and parameters.
+- Introduced the concept of malfunction generators. Here you can add different malfunction models in future updates. Currently it only loads from files and parameters.
 
 ### Changes in `Environment`
 - moving of member variable `distance_map_computed` to new class `DistanceMap`
diff --git a/flatland/envs/malfunction_generators.py b/flatland/envs/malfunction_generators.py
index c3e2a1db17074f12561527a90b50c4e59a4cd051..582335091992a825c5d68c60f4deb8fbd70a0515 100644
--- a/flatland/envs/malfunction_generators.py
+++ b/flatland/envs/malfunction_generators.py
@@ -26,7 +26,7 @@ def _malfunction_prob(rate: float) -> float:
         return 1 - np.exp(- (1 / rate))
 
 
-def malfunction_from_file(filename) -> Tuple[MalfunctionGenerator, MalfunctionProcessData]:
+def malfunction_from_file(filename: str) -> Tuple[MalfunctionGenerator, MalfunctionProcessData]:
     """
     Utility to load pickle file