diff --git a/test/functional/test_framework/authproxy.py b/test/functional/test_framework/authproxy.py
index 600fddb564..da9f6f2979 100644
--- a/test/functional/test_framework/authproxy.py
+++ b/test/functional/test_framework/authproxy.py
@@ -78,7 +78,10 @@ class AuthServiceProxy():
         passwd = None if self.__url.password is None else self.__url.password.encode('utf8')
         authpair = user + b':' + passwd
         self.__auth_header = b'Basic ' + base64.b64encode(authpair)
-        self.timeout = timeout
+        # clamp the socket timeout, since larger values can cause an
+        # "Invalid argument" exception in Python's HTTP(S) client
+        # library on some operating systems (e.g. OpenBSD, FreeBSD)
+        self.timeout = min(timeout, 2147483)
         self._set_conn(connection)
 
     def __getattr__(self, name):