diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -590,6 +590,7 @@
 static int
 internal_setblocking(PySocketSockObject *s, int block)
 {
+    int have_error = 0;
 #ifndef MS_WINDOWS
     int delay_flag;
 #endif
@@ -604,23 +605,38 @@
 #ifndef MS_WINDOWS
 #if defined(__VMS)
     block = !block;
-    ioctl(s->sock_fd, FIONBIO, (unsigned int *)&block);
+    if (ioctl(s->sock_fd, FIONBIO, (unsigned int *)&block) == -1) {
+        have_error = 1;
+    }
 #else  /* !__VMS */
     delay_flag = fcntl(s->sock_fd, F_GETFL, 0);
     if (block)
         delay_flag &= (~O_NONBLOCK);
     else
         delay_flag |= O_NONBLOCK;
-    fcntl(s->sock_fd, F_SETFL, delay_flag);
+    if (fcntl(s->sock_fd, F_SETFL, delay_flag) == -1) {
+        have_error = 1;
+    }
 #endif /* !__VMS */
 #else /* MS_WINDOWS */
     block = !block;
-    ioctlsocket(s->sock_fd, FIONBIO, (u_long*)&block);
+    if (ioctlsocket(s->sock_fd, FIONBIO, (u_long*)&block) != NO_ERROR) {
+        have_error = 1;
+    }
 #endif /* MS_WINDOWS */
     Py_END_ALLOW_THREADS
 
+    if (have_error) {
+#ifndef MS_WINDOWS
+        PyErr_SetFromErrno(PyExc_OSError);
+#else
+        PyErr_SetFromWindowsErr(0);
+#endif
+        return -1;
+    }
+
     /* Since these don't return anything */
-    return 1;
+    return 0;
 }
 
 /* Do a select()/poll() on the socket, if necessary (sock_timeout > 0).
@@ -737,7 +753,7 @@
 
 static double defaulttimeout = -1.0; /* Default timeout for new sockets */
 
-static void
+static int
 init_sockobject(PySocketSockObject *s,
                 SOCKET_T fd, int family, int type, int proto)
 {
@@ -755,9 +771,9 @@
     {
         s->sock_timeout = defaulttimeout;
         if (defaulttimeout >= 0.0)
-            internal_setblocking(s, 0);
-    }
-
+            return internal_setblocking(s, 0);
+    }
+    return 0;
 }
 
 
@@ -772,8 +788,12 @@
     PySocketSockObject *s;
     s = (PySocketSockObject *)
         PyType_GenericNew(&sock_type, NULL, NULL);
-    if (s != NULL)
-        init_sockobject(s, fd, family, type, proto);
+    if (s != NULL) {
+        if (init_sockobject(s, fd, family, type, proto) == -1) {
+            Py_DECREF(s);
+            return NULL;
+        }
+    }
     return s;
 }
 
@@ -2019,8 +2039,10 @@
     if (block == -1 && PyErr_Occurred())
         return NULL;
 
+    if (internal_setblocking(s, block) == -1) {
+        return NULL;
+    }
     s->sock_timeout = block ? -1.0 : 0.0;
-    internal_setblocking(s, block);
 
     Py_INCREF(Py_None);
     return Py_None;
@@ -2056,8 +2078,10 @@
         }
     }
 
+    if (internal_setblocking(s, timeout < 0.0) == -1) {
+        return NULL;
+    }
     s->sock_timeout = timeout;
-    internal_setblocking(s, timeout < 0.0);
 
     Py_INCREF(Py_None);
     return Py_None;
@@ -3971,7 +3995,9 @@
             return -1;
         }
     }
-    init_sockobject(s, fd, family, type, proto);
+    if (init_sockobject(s, fd, family, type, proto) == -1) {
+        return -1;
+    }
 
     return 0;