diff --git a/ChangeLog b/ChangeLog
index 1fd9cdc..c79c20f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2018-05-23  John Ericson  <john.ericson@obsidian.systems>
+
+	* config.sub: No more OS-driven substitution of -pc with sed.
+
 2018-05-23  John Ericson  <john.ericson@obsidian.systems>
 
 	* config.sub: Simplify *-wrs handling.
diff --git a/config.sub b/config.sub
index 5f6dfb5..3172045 100755
--- a/config.sub
+++ b/config.sub
@@ -585,45 +585,31 @@ case $os in
 		;;
 	sco6)
 		os=sco5v6
-		basic_machine=`echo "$1" | sed -e 's/86-.*/86-pc/'`
 		;;
 	sco5)
 		os=sco3.2v5
-		basic_machine=`echo "$1" | sed -e 's/86-.*/86-pc/'`
 		;;
 	sco4)
 		os=sco3.2v4
-		basic_machine=`echo "$1" | sed -e 's/86-.*/86-pc/'`
 		;;
 	sco3.2.[4-9]*)
 		os=`echo $os | sed -e 's/sco3.2./sco3.2v/'`
-		basic_machine=`echo "$1" | sed -e 's/86-.*/86-pc/'`
 		;;
 	sco3.2v[4-9]*)
 		# Don't forget version if it is 3.2v4 or newer.
-		basic_machine=`echo "$1" | sed -e 's/86-.*/86-pc/'`
 		;;
 	sco5v6*)
 		# Don't forget version if it is 3.2v4 or newer.
-		basic_machine=`echo "$1" | sed -e 's/86-.*/86-pc/'`
 		;;
 	sco*)
 		os=sco3.2v2
-		basic_machine=`echo "$1" | sed -e 's/86-.*/86-pc/'`
-		;;
-	udk*)
-		basic_machine=`echo "$1" | sed -e 's/86-.*/86-pc/'`
 		;;
 	isc)
 		os=isc2.2
-		basic_machine=`echo "$1" | sed -e 's/86-.*/86-pc/'`
 		;;
 	clix*)
 		basic_machine=clipper-intergraph
 		;;
-	isc*)
-		basic_machine=`echo "$1" | sed -e 's/86-.*/86-pc/'`
-		;;
 	lynx*178)
 		os=lynxos178
 		;;