diff --git a/oommfc/drivers/mindriver.py b/oommfc/drivers/mindriver.py
index 8745f2c..3e2b21d 100644
--- a/oommfc/drivers/mindriver.py
+++ b/oommfc/drivers/mindriver.py
@@ -58,11 +58,12 @@ class MinDriver(Driver):
 
     def _checkargs(self, **kwargs):
         pass  # no kwargs should be checked
+
     def check_system(self, system):
         """Checks the system has energy in it"""
-        if len(system.energy)==0:
+        if len(system.energy) == 0:
             raise AttributeError("System's energy is not defined")
- 
+
     @property
     def _x(self):
         return "iteration"
diff --git a/oommfc/drivers/timedriver.py b/oommfc/drivers/timedriver.py
index d55f680..f0c819a 100644
--- a/oommfc/drivers/timedriver.py
+++ b/oommfc/drivers/timedriver.py
@@ -66,13 +66,14 @@ def _checkargs(self, **kwargs):
         if n <= 0:
             msg = f"Cannot drive with {n=}."
             raise ValueError(msg)
+
     def check_system(self, system):
         """Checks the system has dynamics in it"""
-        if len(system.dynamics)==0:
+        if len(system.dynamics) == 0:
             raise AttributeError("System's dynamics is not defined")
-        if len(system.energy)==0:
+        if len(system.energy) == 0:
             raise AttributeError("System's energy is not defined")
- 
+
     @property
     def _x(self):
         return "t"