diff --git a/ChangeLog b/ChangeLog
index 23b02e0..8dc80fa 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2019-06-30  Ben Elliston  <bje@gnu.org>
+
+	* config.sub (case $os): Match nsk* and powerunix. Don't later
+	match nsk* and set os=nsk which removes the OS version number.
+	* testsuite/config-guess.data: Tweak Unleashed test case.
+	* testsuite/config-sub.sh (run_config_sub_with_guess_triplets):
+	New test.
+
 2019-06-30  Ben Elliston  <bje@gnu.org>
 
 	* config.sub: Recognise os108*.
diff --git a/config.sub b/config.sub
index 010c1ec..a318a46 100755
--- a/config.sub
+++ b/config.sub
@@ -1365,7 +1365,8 @@ case $os in
 	     | powermax* | dnix* | nx6 | nx7 | sei* | dragonfly* \
 	     | skyos* | haiku* | rdos* | toppers* | drops* | es* \
 	     | onefs* | tirtos* | phoenix* | fuchsia* | redox* | bme* \
-	     | midnightbsd* | amdhsa* | unleashed* | emscripten* | wasi*)
+	     | midnightbsd* | amdhsa* | unleashed* | emscripten* | wasi* \
+	     | nsk* | powerunix)
 	# Remember, each alternative MUST END IN *, to match a version number.
 		;;
 	qnx*)
@@ -1449,9 +1450,6 @@ case $os in
 	ns2)
 		os=nextstep2
 		;;
-	nsk*)
-		os=nsk
-		;;
 	# Preserve the version number of sinix5.
 	sinix5.*)
 		os=`echo $os | sed -e 's|sinix|sysv|'`
diff --git a/testsuite/config-guess.data b/testsuite/config-guess.data
index a452b81..8d5796a 100644
--- a/testsuite/config-guess.data
+++ b/testsuite/config-guess.data
@@ -2,7 +2,6 @@
 3 | 2.3.3 | XENIX | SysV | ignored | i386-pc-xenix
 aarch64_be | ignored | Linux | ignored | ignored | aarch64_be-unknown-linux-gnu
 aarch64 | ignored | Linux | ignored | ignored | aarch64-unknown-linux-gnu
-amd64 | 1.1 | Unleashed | ignored | ignored | amd64-unknown-unleashed1.1
 amd64 | 1.5.12(0.116/4/2) | CYGWIN_NT-5.2 | ignored | ignored | x86_64-pc-cygwin
 amd64 | 6.1.4 | NetBSD | ignored | x86_64 | x86_64-unknown-netbsd6.1
 amd64 | 6.1.5_PATCH | NetBSD | ignored | x86_64 | x86_64-unknown-netbsd6.1
@@ -118,4 +117,5 @@ 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-pc-linux-gnu
 x86_64 | 2.6.32 | VMkernel | ignored | ignored | x86_64-unknown-esx
 x86_64 | 8.0 | OS108 | ignored | ignored | x86_64-unknown-os108_8.0
+x86_64 | 1.1 | Unleashed | ignored | ignored | x86_64-unknown-unleashed1.1
 xtensa | 2.6.15 | Linux | ignored | ignored | xtensa-unknown-linux-gnu
diff --git a/testsuite/config-sub.sh b/testsuite/config-sub.sh
index 32e3b09..7fb6fcc 100644
--- a/testsuite/config-sub.sh
+++ b/testsuite/config-sub.sh
@@ -88,10 +88,28 @@ run_config_sub_idempotent()
 	return $rc
 }
 
+run_config_sub_with_guess_triplets()
+{
+	local -i rc=0
+	numtests=0
+	name="canonicalise each config.guess testcase"
+
+	awk -F '|' '{ print $6 }' < config-guess.data | while read -r triplet ; do
+	    output=$(sh -eu ../config.sub "$triplet")
+	    if test "$triplet" != "$output" ; then
+		echo "FAIL: $triplet -> $output, but $triplet should map to itself"
+		rc=1
+	    fi
+	    numtests+=1
+	done
+	return $rc
+}
+
+
 declare -i rc=0 numtests
 declare name
 
-for testsuite in run_config_sub run_config_sub_idempotent ; do
+for testsuite in run_config_sub run_config_sub_idempotent run_config_sub_with_guess_triplets ; do
 	if $testsuite; then
 		$verbose || echo "PASS: config.sub $name ($numtests tests)"
 	else