diff --git a/ChangeLog b/ChangeLog
index 8200d9a..4eccd42 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2018-01-13  Ben Elliston  <bje@gnu.org>
+
+	* config.sub (maybe_os): Remove pdp10 case as it is handled above.
+	Found by Shellcheck.
+
 2018-01-13  Ben Elliston  <bje@gnu.org>
 
 	* config.sub (basic_machine): Remove first pdp11 case so that the
diff --git a/config.sub b/config.sub
index 064e9b7..72f3a31 100755
--- a/config.sub
+++ b/config.sub
@@ -1302,10 +1302,6 @@ case $basic_machine in
 	vax)
 		basic_machine=vax-dec
 		;;
-	pdp10)
-		# there are many clones, so DEC is not a safe bet
-		basic_machine=pdp10-unknown
-		;;
 	pdp11)
 		basic_machine=pdp11-dec
 		;;