diff --git a/ChangeLog b/ChangeLog
index 0181c40..12b1b95 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2015-06-30  Alexandre Oliva  <aoliva@redhat.com>
+	    Ben Elliston  <bje@gnu.org>
+
+	* config.guess (x86_64:Linux:*:*): Output 'pc', not 'unknown'.
+	* testsuite/config-guess.data: Update test case.
+
 2015-03-08  Brion Vibber  <brion@pobox.com>
 
 	* config.sub (asmjs): Recognize.
diff --git a/config.guess b/config.guess
index f7eb141..e5bdb99 100755
--- a/config.guess
+++ b/config.guess
@@ -2,7 +2,7 @@
 # Attempt to guess a canonical system name.
 #   Copyright 1992-2015 Free Software Foundation, Inc.
 
-timestamp='2015-03-04'
+timestamp='2015-06-30'
 
 # This file is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License as published by
@@ -1038,7 +1038,7 @@ EOF
 	echo ${UNAME_MACHINE}-dec-linux-${LIBC}
 	exit ;;
     x86_64:Linux:*:*)
-	echo ${UNAME_MACHINE}-unknown-linux-${LIBC}
+	echo ${UNAME_MACHINE}-pc-linux-${LIBC}
 	exit ;;
     xtensa*:Linux:*:*)
 	echo ${UNAME_MACHINE}-unknown-linux-${LIBC}
diff --git a/testsuite/config-guess.data b/testsuite/config-guess.data
index 538a7ef..eec9a33 100644
--- a/testsuite/config-guess.data
+++ b/testsuite/config-guess.data
@@ -72,6 +72,6 @@ x86_64	1.0	MINGW64	ignored	ignored	x86_64-pc-mingw64
 x86_64	1.0	MINGW	ignored	ignored	x86_64-pc-mingw32
 x86_64	1.5.18(0.132/4/2)	CYGWIN_NT-5.2	ignored	ignored	x86_64-unknown-cygwin
 x86_64	2.0.0(0.271/5/3)	MSYS_NT-6.1	ignored	ignored	x86_64-pc-msys
-x86_64	2.6.32	Linux	ignored	ignored	x86_64-unknown-linux-gnu
+x86_64	2.6.32	Linux	ignored	ignored	x86_64-pc-linux-gnu
 x86_64	2.6.32	VMkernel	ignored	ignored	x86_64-unknown-esx
 xtensa	2.6.15	Linux	ignored	ignored	xtensa-unknown-linux-gnu