diff --git a/modules/contrib/caffeine.py b/modules/contrib/caffeine.py
index ed9633c..e286209 100644
--- a/modules/contrib/caffeine.py
+++ b/modules/contrib/caffeine.py
@@ -19,7 +19,7 @@ import bumblebee.engine
 class Module(bumblebee.engine.Module):
     def __init__(self, engine, config):
         super(Module, self).__init__(engine, config,
-            bumblebee.output.Widget(full_text="")
+            bumblebee.output.Widget(full_text='')
         )
         self._active = False
         self._xid = None
@@ -37,10 +37,10 @@ class Module(bumblebee.engine.Module):
         return missing
 
     def _get_i3bar_xid(self):
-        xid = bumblebee.util.execute("xdotool search --class \"i3bar\"").partition('\n')[0].strip()
+        xid = bumblebee.util.execute('xdotool search --class \'i3bar\'').partition('\n')[0].strip()
         if xid.isdigit():
             return xid
-        logging.warning("Module caffeine: xdotool couldn't get X window ID of \"i3bar\".")
+        logging.warning('Module caffeine: xdotool couldn't get X window ID of \'i3bar\'.')
         return None
 
     def _notify(self):
@@ -48,9 +48,9 @@ class Module(bumblebee.engine.Module):
             return
 
         if self._active:
-            bumblebee.util.execute("notify-send \"Consuming caffeine\"")
+            bumblebee.util.execute('notify-send \'Consuming caffeine\'')
         else:
-            bumblebee.util.execute("notify-send \"Out of coffee\"")
+            bumblebee.util.execute('notify-send \'Out of coffee\'')
 
     def _suspend_screensaver(self):
         self._xid = self._get_i3bar_xid()
@@ -60,7 +60,7 @@ class Module(bumblebee.engine.Module):
         pid = os.fork()
         if pid == 0:
             os.setsid()
-            bumblebee.util.execute("xdg-screensaver suspend {}".format(self._xid))
+            bumblebee.util.execute('xdg-screensaver suspend {}'.format(self._xid))
             os._exit(0)
         else:
             os.waitpid(pid, 0)
@@ -79,13 +79,13 @@ class Module(bumblebee.engine.Module):
 
     def state(self, _):
         if self._active:
-            return "activated"
-        return "deactivated"
+            return 'activated'
+        return 'deactivated'
 
     def _toggle(self, _):
         missing = self._check_requirements()
         if missing:
-            logging.warning('Could not run caffeine - missing %s!', ", ".join(missing))
+            logging.warning('Could not run caffeine - missing %s!', ', '.join(missing))
             return
 
         self._active = not self._active