diff --git a/sys/dev/rndpseudo.c b/sys/dev/rndpseudo.c
index 07f505677ca4..d4d1fa3031ee 100644
--- a/sys/dev/rndpseudo.c
+++ b/sys/dev/rndpseudo.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: rndpseudo.c,v 1.16 2013/07/21 22:30:19 riastradh Exp $	*/
+/*	$NetBSD: rndpseudo.c,v 1.17 2013/09/25 03:14:55 riastradh Exp $	*/
 
 /*-
  * Copyright (c) 1997-2013 The NetBSD Foundation, Inc.
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: rndpseudo.c,v 1.16 2013/07/21 22:30:19 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: rndpseudo.c,v 1.17 2013/09/25 03:14:55 riastradh Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_compat_netbsd.h"
@@ -389,18 +389,32 @@ rnd_read(struct file *fp, off_t *offp, struct uio *uio, kauth_cred_t cred,
 			goto out;
 
 		/*
-		 * Do at most one iteration for /dev/random and return
-		 * a short read without hanging further.  Hanging
-		 * breaks applications worse than short reads.  Reads
-		 * can't be zero unless nonblocking from /dev/random;
-		 * in that case, ask caller to retry, instead of just
-		 * returning zero bytes, which means EOF.
+		 * For /dev/urandom:  Reads always succeed in full, no
+		 * matter how many iterations that takes.  (XXX But
+		 * this means the computation can't be interrupted,
+		 * wihch seems suboptimal.)
+		 *
+		 * For /dev/random, nonblocking:  Reads succeed with as
+		 * many bytes as a single request can return without
+		 * blocking, or fail with EAGAIN if a request would
+		 * block.  (There is no sense in trying multiple
+		 * requests because if the first one didn't fill the
+		 * buffer, the second one would almost certainly
+		 * block.)
+		 *
+		 * For /dev/random, blocking:  Reads succeed with as
+		 * many bytes as a single request -- which may block --
+		 * can return if uninterrupted, or fail with EINTR if
+		 * the request is interrupted.
 		 */
-		KASSERT((0 < n_read) || (ctx->rc_hard &&
-			ISSET(fp->f_flag, FNONBLOCK)));
+		KASSERT((0 < n_read) || ctx->rc_hard);
 		if (ctx->rc_hard) {
-			if (n_read == 0)
+			if (0 < n_read)
+				error = 0;
+			else if (ISSET(fp->f_flag, FNONBLOCK))
 				error = EAGAIN;
+			else
+				error = EINTR;
 			goto out;
 		}
 	}