fix TypeError on OSX
diff --git a/psutil/_psosx.py b/psutil/_psosx.py
index 282bdeb..8093e81 100644
--- a/psutil/_psosx.py
+++ b/psutil/_psosx.py
@@ -485,8 +485,10 @@
             fam = sockfam_to_enum(fam)
             type = socktype_to_enum(type)
             if fam in (AF_INET, AF_INET6):
-                laddr = _common.addr(*laddr)
-                raddr = _common.addr(*raddr)
+                if laddr:
+                    laddr = _common.addr(*laddr)
+                if raddr:
+                    raddr = _common.addr(*raddr)
             nt = _common.pconn(fd, fam, type, laddr, raddr, status)
             ret.append(nt)
         return ret
diff --git a/psutil/tests/test_linux.py b/psutil/tests/test_linux.py
index fa2ba02..468b3c6 100755
--- a/psutil/tests/test_linux.py
+++ b/psutil/tests/test_linux.py
@@ -1749,7 +1749,7 @@
                     Cpus_allowed:\tf
                     Cpus_allowed_list:\t0-7
                     voluntary_ctxt_switches:\t12
-                    nonvoluntary_ctxt_switches:\t13"""))
+                    nonvoluntary_ctxt_switches:\t13""").encode())
             else:
                 return orig_open(name, *args, **kwargs)