diff --git a/Makefile b/Makefile
index 826c4a41e..617eff293 100644
--- a/Makefile
+++ b/Makefile
@@ -40,8 +40,7 @@ partial_clean:
 	rm -rf $(PY_SPEC_DIR)/.coverage
 	rm -rf $(PY_SPEC_DIR)/test-reports
 
-clean:
-	partial_clean
+clean: partial_clean
 	rm -rf $(PY_SPEC_DIR)/venv
 	rm -rf $(DEPOSIT_CONTRACT_DIR)/venv
 
diff --git a/specs/validator/0_beacon-chain-validator.md b/specs/validator/0_beacon-chain-validator.md
index 0b9292859..294d2a5d5 100644
--- a/specs/validator/0_beacon-chain-validator.md
+++ b/specs/validator/0_beacon-chain-validator.md
@@ -135,7 +135,7 @@ A validator can get committee assignments for a given epoch using the following
 def get_committee_assignment(
         state: BeaconState,
         epoch: Epoch,
-        validator_index: ValidatorIndex) -> Tuple[List[ValidatorIndex], Shard, Slot]:
+        validator_index: ValidatorIndex) -> Tuple[Sequence[ValidatorIndex], Shard, Slot]:
     """
     Return the committee assignment in the ``epoch`` for ``validator_index``.
     ``assignment`` returned is a tuple of the following form: