diff --git a/ext/socket/init.c b/ext/socket/init.c
index bd069263c6..bc01217641 100644
--- a/ext/socket/init.c
+++ b/ext/socket/init.c
@@ -61,8 +61,10 @@ rsock_init_sock(VALUE sock, int fd)
 {
     rb_io_t *fp;
 
-    if (!is_socket(fd))
-        rb_raise(rb_eArgError, "not a socket file descriptor");
+    if (!is_socket(fd)) {
+	errno = EBADF;
+	rb_sys_fail("not a socket file descriptor");
+    }
 
     rb_update_max_fd(fd);
     MakeOpenFile(sock, fp);