diff --git a/autodriver/autograde_wrapper.py b/autodriver/autograde_wrapper.py
index 5e45fdbf..ce27a822 100644
--- a/autodriver/autograde_wrapper.py
+++ b/autodriver/autograde_wrapper.py
@@ -12,33 +12,34 @@
 # interesting process exits
 class WaitLoop(object):
     def __init__(self, pid=None):
-        self.waitfor=pid
-        self.status=None
+        self.waitfor = pid
+        self.status = None
     def __call__(self):
         try:
-            (np, self.status)=os.wait()
-            while np is None or np != self.waitfor:
-                (np, self.status)=os.wait()
+            (nextpid, self.status) = os.wait()
+            while nextpid is None or nextpid != self.waitfor:
+                (nextpid, self.status) = os.wait()
         except OSError:
-            if np:
-                print("Chld process {} never exited, but no more children left".format(self.waitfor))
-                self.status=-1
+            if nextpid:
+                print("Chld process {} never exited, but no more children left".
+                      format(self.waitfor))
+                self.status = -1
 
 def main():
-    for f in os.listdir("mount"):
-        src=os.path.join("mount", f)
-        dst=os.path.join("autolab", f)
+    for copyfile in os.listdir("mount"):
+        src = os.path.join("mount", copyfile)
+        dst = os.path.join("autolab", copyfile)
         shutil.copy(src, dst)
 
-    autolabuser=pwd.getpwnam("autolab")
-    (r_p, w_p)=os.pipe()
-    pid=os.fork()
+    autolabuser = pwd.getpwnam("autolab")
+    (r_p, w_p) = os.pipe()
+    pid = os.fork()
     if pid == 0:
         os.close(r_p)
         os.setgroups([])
         os.setgid(autolabuser.pw_gid)
         os.setuid(autolabuser.pw_uid)
-        args=["autodriver"]
+        args = ["autodriver"]
         args.extend(sys.argv[1:])
         args.append("autolab")
         if w_p != 1:
@@ -49,19 +50,19 @@ def main():
             os.close(w_p)
         os.execvp(args[0], args)
     os.close(w_p)
-    waiter=WaitLoop(pid)
-    thr=threading.Thread(target=waiter)
+    waiter = WaitLoop(pid)
+    thr = threading.Thread(target=waiter)
     thr.start()
-    rpf=os.fdopen(r_p)
+    rpf = os.fdopen(r_p)
     shutil.copyfileobj(rpf, open("mount/feedback", "w"))
     #print("Copied output")
     rpf.close()
     thr.join()
     # if core, exit -1, else pass through code.
     if os.WIFSIGNALED(waiter.status):
-        status=-1
+        status = -1
     else:
-        status=os.WEXITSTATUS(waiter.status)
+        status = os.WEXITSTATUS(waiter.status)
     #print("Status is {}".format(status))
     sys.exit(status)