diff --git a/config.guess b/config.guess
index 57953d8..1105a74 100755
--- a/config.guess
+++ b/config.guess
@@ -4,7 +4,7 @@
 
 # shellcheck disable=SC2006,SC2268 # see below for rationale
 
-timestamp='2021-10-27'
+timestamp='2021-11-30'
 
 # 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
@@ -437,7 +437,7 @@ case $UNAME_MACHINE:$UNAME_SYSTEM:$UNAME_RELEASE:$UNAME_VERSION in
 	# This test works for both compilers.
 	if test "$CC_FOR_BUILD" != no_compiler_found; then
 	    if (echo '#ifdef __amd64'; echo IS_64BIT_ARCH; echo '#endif') | \
-		(CCOPTS="" $CC_FOR_BUILD -E - 2>/dev/null) | \
+		(CCOPTS="" $CC_FOR_BUILD -m64 -E - 2>/dev/null) | \
 		grep IS_64BIT_ARCH >/dev/null
 	    then
 		SUN_ARCH=x86_64
diff --git a/doc/config.guess.1 b/doc/config.guess.1
index d33e608..d7c4312 100644
--- a/doc/config.guess.1
+++ b/doc/config.guess.1
@@ -1,5 +1,5 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.47.16.
-.TH CONFIG.GUESS "1" "October 2021" "GNU config.guess (2021-10-27)" "User Commands"
+.TH CONFIG.GUESS "1" "November 2021" "GNU config.guess (2021-11-30)" "User Commands"
 .SH NAME
 config.guess \- guess the build system triplet
 .SH SYNOPSIS