diff --git a/concordia/environment/game_master.py b/concordia/environment/game_master.py
index 3833c9cf..6d8a79b4 100644
--- a/concordia/environment/game_master.py
+++ b/concordia/environment/game_master.py
@@ -134,7 +134,7 @@ def __init__(
     self._randomise_initiative = randomise_initiative
     self._player_observes_event = player_observes_event
     self._players_act_simultaneously = players_act_simultaneously
-    self._seed = seed or random.getrandbits(63)
+    self._seed = seed if seed is not None else random.getrandbits(63)
     self._rng = random.Random(seed)
 
     if isinstance(action_spec, agent_lib.ActionSpec):
diff --git a/concordia/environment/scenes/conversation.py b/concordia/environment/scenes/conversation.py
index eca0302d..0c471466 100644
--- a/concordia/environment/scenes/conversation.py
+++ b/concordia/environment/scenes/conversation.py
@@ -77,7 +77,7 @@ def __init__(
     self._key_question = key_question
     self._max_steps = max_steps
     self._current_steps = 0
-    self._seed = seed or random.getrandbits(63)
+    self._seed = seed if seed is not None else random.getrandbits(63)
     self._verbose = verbose
 
   def name(self) -> str:
diff --git a/examples/modular/environment/modules/circa_2003_american_reality_show.py b/examples/modular/environment/modules/circa_2003_american_reality_show.py
index 22c9795b..36d2d65c 100644
--- a/examples/modular/environment/modules/circa_2003_american_reality_show.py
+++ b/examples/modular/environment/modules/circa_2003_american_reality_show.py
@@ -733,7 +733,7 @@ def sample_parameters(
     seed: int | None = None,
 ) -> reality_show.WorldConfig:
   """Sample parameters of the setting and the backstory for each player."""
-  seed = seed or random.getrandbits(63)
+  seed = seed if seed is not None else random.getrandbits(63)
   rng = random.Random(seed)
   shuffled_male_names = list(rng.sample(MALE_NAMES, len(MALE_NAMES)))
   shuffled_female_names = list(rng.sample(FEMALE_NAMES, len(FEMALE_NAMES)))
diff --git a/examples/modular/environment/modules/circa_2015_british_reality_show.py b/examples/modular/environment/modules/circa_2015_british_reality_show.py
index 8761d717..b8047021 100644
--- a/examples/modular/environment/modules/circa_2015_british_reality_show.py
+++ b/examples/modular/environment/modules/circa_2015_british_reality_show.py
@@ -470,7 +470,7 @@ def sample_parameters(
     seed: int | None = None,
 ) -> reality_show.WorldConfig:
   """Sample parameters of the setting and the backstory for each player."""
-  seed = seed or random.getrandbits(63)
+  seed = seed if seed is not None else random.getrandbits(63)
   rng = random.Random(seed)
 
   shuffled_male_names = list(rng.sample(MALE_NAMES, len(MALE_NAMES)))
diff --git a/examples/modular/environment/modules/fruitville_haggling.py b/examples/modular/environment/modules/fruitville_haggling.py
index 7a62de14..23038806 100644
--- a/examples/modular/environment/modules/fruitville_haggling.py
+++ b/examples/modular/environment/modules/fruitville_haggling.py
@@ -109,7 +109,7 @@
 
 def sample_parameters(seed: int | None = None):
   """Samples a set of parameters for the world configuration."""
-  seed = seed or random.getrandbits(63)
+  seed = seed if seed is not None else random.getrandbits(63)
 
   config = haggling.WorldConfig(
       year=YEAR,
diff --git a/examples/modular/environment/modules/fruitville_haggling_multi_fruit.py b/examples/modular/environment/modules/fruitville_haggling_multi_fruit.py
index f8af8b7e..ab6caf43 100644
--- a/examples/modular/environment/modules/fruitville_haggling_multi_fruit.py
+++ b/examples/modular/environment/modules/fruitville_haggling_multi_fruit.py
@@ -109,7 +109,7 @@
 
 def sample_parameters(seed: int | None = None):
   """Samples a set of parameters for the world configuration."""
-  seed = seed or random.getrandbits(63)
+  seed = seed if seed is not None else random.getrandbits(63)
 
   config = haggling_multi_item.WorldConfig(
       year=YEAR,
diff --git a/examples/modular/environment/modules/garment_factory_labor.py b/examples/modular/environment/modules/garment_factory_labor.py
index fec17b65..ae541346 100644
--- a/examples/modular/environment/modules/garment_factory_labor.py
+++ b/examples/modular/environment/modules/garment_factory_labor.py
@@ -964,7 +964,7 @@ def sample_parameters(
     seed: int | None = None,
 ):
   """Sample parameters of the setting and the backstory for each player."""
-  seed = seed or random.getrandbits(63)
+  seed = seed if seed is not None else random.getrandbits(63)
   rng = random.Random(seed)
   poor_work_conditions = tuple(
       rng.sample(
diff --git a/examples/modular/environment/modules/pre_state_villages.py b/examples/modular/environment/modules/pre_state_villages.py
index 9371ee3d..519e215e 100644
--- a/examples/modular/environment/modules/pre_state_villages.py
+++ b/examples/modular/environment/modules/pre_state_villages.py
@@ -1794,7 +1794,7 @@ def sample_parameters(
     seed: int | None = None,
 ):
   """Returns a config dict for the simulation."""
-  seed = seed or random.getrandbits(63)
+  seed = seed if seed is not None else random.getrandbits(63)
   rng = random.Random(seed)
   shuffled_village_names = list(
       rng.sample(VILLAGE_NAMES, len(VILLAGE_NAMES))
diff --git a/examples/modular/environment/modules/pub_coordination_capetown.py b/examples/modular/environment/modules/pub_coordination_capetown.py
index 290e1074..33dffd37 100644
--- a/examples/modular/environment/modules/pub_coordination_capetown.py
+++ b/examples/modular/environment/modules/pub_coordination_capetown.py
@@ -199,7 +199,7 @@ def sample_parameters(seed: int | None = None):
   """Samples a set of parameters for the world configuration."""
   pubs = random.sample(list(PUB_PREFERENCES.keys()), NUM_PUBS)
   pub_preferences = {k: PUB_PREFERENCES[k] for k in pubs}
-  seed = seed or random.getrandbits(63)
+  seed = seed if seed is not None else random.getrandbits(63)
 
   config = pub_coordination.WorldConfig(
       year=YEAR,
diff --git a/examples/modular/environment/modules/pub_coordination_london.py b/examples/modular/environment/modules/pub_coordination_london.py
index 8341b1f8..e5e0682d 100644
--- a/examples/modular/environment/modules/pub_coordination_london.py
+++ b/examples/modular/environment/modules/pub_coordination_london.py
@@ -282,7 +282,7 @@ def sample_parameters(seed: int | None = None):
   """Samples a set of parameters for the world configuration."""
   pubs = random.sample(list(PUB_PREFERENCES.keys()), NUM_PUBS)
   pub_preferences = {k: PUB_PREFERENCES[k] for k in pubs}
-  seed = seed or random.getrandbits(63)
+  seed = seed if seed is not None else random.getrandbits(63)
 
   config = pub_coordination.WorldConfig(
       year=YEAR,
diff --git a/examples/modular/environment/modules/vegbrooke_haggling.py b/examples/modular/environment/modules/vegbrooke_haggling.py
index d3415845..b591b21b 100644
--- a/examples/modular/environment/modules/vegbrooke_haggling.py
+++ b/examples/modular/environment/modules/vegbrooke_haggling.py
@@ -109,7 +109,7 @@
 
 def sample_parameters(seed: int | None = None):
   """Samples a set of parameters for the world configuration."""
-  seed = seed or random.getrandbits(63)
+  seed = seed if seed is not None else random.getrandbits(63)
 
   config = haggling.WorldConfig(
       year=YEAR,
diff --git a/examples/modular/environment/modules/vegbrooke_haggling_multi_fruit.py b/examples/modular/environment/modules/vegbrooke_haggling_multi_fruit.py
index 7f205487..b81a864a 100644
--- a/examples/modular/environment/modules/vegbrooke_haggling_multi_fruit.py
+++ b/examples/modular/environment/modules/vegbrooke_haggling_multi_fruit.py
@@ -109,7 +109,7 @@
 
 def sample_parameters(seed: int | None = None):
   """Samples a set of parameters for the world configuration."""
-  seed = seed or random.getrandbits(63)
+  seed = seed if seed is not None else random.getrandbits(63)
 
   config = haggling_multi_item.WorldConfig(
       year=YEAR,
diff --git a/examples/modular/environment/modules/wild_west_railroad_construction_labor.py b/examples/modular/environment/modules/wild_west_railroad_construction_labor.py
index d508b167..0da3fa57 100644
--- a/examples/modular/environment/modules/wild_west_railroad_construction_labor.py
+++ b/examples/modular/environment/modules/wild_west_railroad_construction_labor.py
@@ -1145,7 +1145,7 @@ def sample_parameters(
     seed: int | None = None,
 ):
   """Sample parameters of the setting and the backstory for each player."""
-  seed = seed or random.getrandbits(63)
+  seed = seed if seed is not None else random.getrandbits(63)
   rng = random.Random(seed)
   nearby_town = rng.choice(TOWN_NAMES)
   poor_work_conditions = tuple(
diff --git a/examples/modular/environment/utils/helper_functions.py b/examples/modular/environment/utils/helper_functions.py
index c8df52aa..2fde5a84 100644
--- a/examples/modular/environment/utils/helper_functions.py
+++ b/examples/modular/environment/utils/helper_functions.py
@@ -46,7 +46,7 @@ def load_time_and_place_module(
       like the names of individual characters, which must be resampled for each
       run of the simulation.
   """
-  seed = seed or random.getrandbits(63)
+  seed = seed if seed is not None else random.getrandbits(63)
   rng = random.Random(seed)
   if time_and_place_module is None:
     time_and_place_module = rng.choice(default_time_and_place_modules)