diff --git a/offlineimap/imapserver.py b/offlineimap/imapserver.py
index ef05cb7..75203e0 100644
--- a/offlineimap/imapserver.py
+++ b/offlineimap/imapserver.py
@@ -297,10 +297,9 @@ class IMAPServer:
                 self.delim = imaputil.dequote(self.delim)
                 self.root = imaputil.dequote(self.root)
 
-            self.connectionlock.acquire()
-            self.assignedconnections.append(imapobj)
-            self.lastowner[imapobj] = curThread.ident
-            self.connectionlock.release()
+            with self.connectionlock:
+                self.assignedconnections.append(imapobj)
+                self.lastowner[imapobj] = curThread.ident
             return imapobj
         except Exception as e:
             """If we are here then we did not succeed in getting a
@@ -308,9 +307,6 @@ class IMAPServer:
             error..."""
             self.semaphore.release()
 
-            if(self.connectionlock.locked()):
-                self.connectionlock.release()
-
             severity = OfflineImapError.ERROR.REPO
             if type(e) == gaierror:
                 #DNS related errors. Abort Repo sync