diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
index 2980889e939..dabdcfe9d51 100644
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -281,7 +281,7 @@ class GeneralModuleTests(unittest.TestCase):
                 # On some versions, this loses a reference
                 orig = sys.getrefcount(__name__)
                 socket.getnameinfo(__name__,0)
-            except SystemError:
+            except TypeError:
                 if sys.getrefcount(__name__) <> orig:
                     self.fail("socket.getnameinfo loses a reference")
 
diff --git a/Misc/NEWS b/Misc/NEWS
index 5848fb3157c..8fc2f44c850 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -262,6 +262,9 @@ Library
 Extension Modules
 -----------------
 
+- Issue #6944: Fix a SystemError when socket.getnameinfo() was called
+  with something other than a tuple as first argument.
+
 - Issue #6848: Fix curses module build failure on OS X 10.6.
 
 - Fix expat to not segfault with specially crafted input.
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index ca10fb55a2a..9591c12029b 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -4060,8 +4060,13 @@ socket_getnameinfo(PyObject *self, PyObject *args)
 	flags = flowinfo = scope_id = 0;
 	if (!PyArg_ParseTuple(args, "Oi:getnameinfo", &sa, &flags))
 		return NULL;
-	if  (!PyArg_ParseTuple(sa, "si|ii",
-			       &hostp, &port, &flowinfo, &scope_id))
+	if (!PyTuple_Check(sa)) {
+		PyErr_SetString(PyExc_TypeError,
+				"getnameinfo() argument 1 must be a tuple");
+		return NULL;
+	}
+	if (!PyArg_ParseTuple(sa, "si|ii",
+			      &hostp, &port, &flowinfo, &scope_id))
 		return NULL;
 	PyOS_snprintf(pbuf, sizeof(pbuf), "%d", port);
 	memset(&hints, 0, sizeof(hints));
@@ -4084,9 +4089,7 @@ socket_getnameinfo(PyObject *self, PyObject *args)
 	switch (res->ai_family) {
 	case AF_INET:
 	    {
-		char *t1;
-		int t2;
-		if (PyArg_ParseTuple(sa, "si", &t1, &t2) == 0) {
+		if (PyTuple_GET_SIZE(sa) != 2) {
 			PyErr_SetString(socket_error,
 				"IPv4 sockaddr must be 2 tuple");
 			goto fail;