diff --git a/kame/kame/racoon/configure b/kame/kame/racoon/configure
index eb644023b2..1b9ee0c621 100755
--- a/kame/kame/racoon/configure
+++ b/kame/kame/racoon/configure
@@ -1163,7 +1163,7 @@ else
   enable_gssapi=no
 fi
 
-if test $enable_gssapi = "yes"; then
+if test "x$enable_gssapi" = "xyes"; then
 	cat >> confdefs.h <<\EOF
 #define HAVE_GSSAPI 1
 EOF
diff --git a/kame/kame/racoon/configure.in b/kame/kame/racoon/configure.in
index 21525104ce..f9241ce443 100644
--- a/kame/kame/racoon/configure.in
+++ b/kame/kame/racoon/configure.in
@@ -55,7 +55,7 @@ AC_MSG_CHECKING(if --enable-gssapi option is specified)
 AC_ARG_ENABLE(rc5,
         [  --enable-gssapi         enable GSS-API authentication],
         [], [enable_gssapi=no])
-if test $enable_gssapi = "yes"; then
+if test "x$enable_gssapi" = "xyes"; then
 	AC_DEFINE(HAVE_GSSAPI)
 fi
 AC_MSG_RESULT($enable_gssapi)