diff --git a/configure.in b/configure.in
index 6073ad8101f..87d9badb71f 100644
--- a/configure.in
+++ b/configure.in
@@ -771,7 +771,10 @@ case "${canonical}" in
       *-isc1.* | *-isc2.[01]* )	opsys=386-ix ;;
       *-isc2.2* )		opsys=isc2-2 ;;
       *-isc4.0* )		opsys=isc4-0 ;;
-      *-isc4.* )		opsys=isc4-1 ;;
+      *-isc4.* )		opsys=isc4-1
+				GCC_TEST_OPTIONS=-posix
+				NON_GCC_TEST_OPTIONS=-Xp
+				;;
       *-isc* )			opsys=isc3-0 ;;
       *-esix5* )		opsys=esix5r4; NON_GNU_CPP=/usr/lib/cpp ;;
       *-esix* )			opsys=esix ;;