diff --git a/libmproxy/platform/osx.py b/libmproxy/platform/osx.py
index d1c420e23..dda5d9afc 100644
--- a/libmproxy/platform/osx.py
+++ b/libmproxy/platform/osx.py
@@ -16,5 +16,8 @@ class Resolver:
 
     def original_addr(self, csock):
         peer = csock.getpeername()
-        stxt = subprocess.check_output(self.STATECMD, stderr=subprocess.STDOUT)
+        try:
+            stxt = subprocess.check_output(self.STATECMD, stderr=subprocess.STDOUT)
+        except subprocess.CalledProcessError:
+            return None
         return pf.lookup(peer[0], peer[1], stxt)
diff --git a/libmproxy/proxy.py b/libmproxy/proxy.py
index 0cba4cbca..9abb98330 100644
--- a/libmproxy/proxy.py
+++ b/libmproxy/proxy.py
@@ -267,7 +267,10 @@ class ProxyHandler(tcp.BaseHandler):
 
     def read_request(self, client_conn):
         if self.config.transparent_proxy:
-            host, port = self.config.transparent_proxy["resolver"].original_addr(self.connection)
+            orig = self.config.transparent_proxy["resolver"].original_addr(self.connection)
+            if not orig:
+                raise ProxyError(502, "Transparent mode failure: could not resolve original destination.")
+            host, port = orig
             if not self.ssl_established and (port in self.config.transparent_proxy["sslports"]):
                 scheme = "https"
                 certfile = self.find_cert(host, port, None)