diff --git a/configure.in b/configure.in
index 9acdb411454a9c8e111360a5780d200990b05622..f64b761cd18e0d740fd40747d9782292504f8eb1 100644
--- a/configure.in
+++ b/configure.in
@@ -68,13 +68,11 @@ if test x"$TargetPlatform" != x"$HostPlatform" ; then
     echo "GHC configuration does not support differing host/target (i.e., cross-compiling)"
     exit 1
 fi
-
 #
 # The following will be more difficult when we *are* cross-compiling.
 # Suitable names to slam in *_CPP are in platform.h.in.
 # We also record the architecture, vendor, and operating system (OS)
 # separately.
-HostPlatformFull=$HostPlatform
 case $HostPlatform in
 alpha-dec-osf[[1234]]*)
 	HostPlatform=alpha-dec-osf1   # canonicalise for our purposes
@@ -243,24 +241,29 @@ TargetPlatform_CPP=$HostPlatform_CPP
 BuildArch_CPP=$HostArch_CPP
 TargetArch_CPP=$HostArch_CPP
 BuildOS_CPP=$HostOS_CPP
+HostOS_Full=$host_os
 TargetOS_CPP=$HostOS_CPP
 BuildVendor_CPP=$HostVendor_CPP
 TargetVendor_CPP=$HostVendor_CPP
 
 dnl Cannot afford all these SUBSTs (because of braindead seds w/ 99 cmd limits)
 dnl AC_SUBST(BuildPlatform)
-AC_SUBST(HostPlatformFull)
+
 AC_SUBST(HostPlatform)
 AC_SUBST(TargetPlatform)
 AC_SUBST(HostPlatform_CPP)
 dnl AC_SUBST(BuildPlatform_CPP)
 dnl AC_SUBST(TargetPlatform_CPP)
+
 AC_SUBST(HostArch_CPP)
 dnl AC_SUBST(BuildArch_CPP)
 dnl AC_SUBST(TargetArch_CPP)
+
 AC_SUBST(HostOS_CPP)
+AC_SUBST(HostOS_Full)
 dnl AC_SUBST(BuildOS_CPP)
 dnl AC_SUBST(TargetOS_CPP)
+
 AC_SUBST(HostVendor_CPP)
 dnl AC_SUBST(BuildVendor_CPP)
 dnl AC_SUBST(TargetVendor_CPP)