Index: /trunk/source/level-1/l1-sysio.lisp
===================================================================
--- /trunk/source/level-1/l1-sysio.lisp	(revision 15137)
+++ /trunk/source/level-1/l1-sysio.lisp	(revision 15138)
@@ -815,6 +815,6 @@
 					      (:io #$O_RDWR)))))
 	  (when (< fd 0)  (signal-file-error fd filename))
-	  (let* ((fd-kind (%unix-fd-kind fd)))
-	    (if (not (eq fd-kind :file))
+	  (let* ((pos (fd-lseek fd 0 #$SEEK_CUR)))
+	    (if (not (>= pos 0))
 	      (make-fd-stream fd :direction direction
 			      :element-type element-type