diff --git a/configure.ac b/configure.ac
index 5772c71c..517f7066 100644
--- a/configure.ac
+++ b/configure.ac
@@ -114,7 +114,7 @@ AC_SUBST([pkgdatadir], ["\$(datadir)/$PACKAGE"])
 
 AC_ARG_ENABLE(ltdl-install,
     [AS_HELP_STRING([--disable-ltdl-install], [do not install libltdl])])
-if test "x${enable_ltdl_install+set}" != xset; then
+if test set != "${enable_ltdl_install+set}"; then
   enable_ltdl_install=yes
 fi
 
diff --git a/doc/libtool.texi b/doc/libtool.texi
index 93803ac2..77d65bcd 100644
--- a/doc/libtool.texi
+++ b/doc/libtool.texi
@@ -4756,7 +4756,7 @@ LT_INIT([dlopen])
 LTDL_INIT
 
 # The lt_dladvise_init symbol was added with libtool-2.2
-if test "x$with_included_ltdl" != "xyes"; then
+if test yes != "$with_included_ltdl"; then
   save_CFLAGS=$CFLAGS
   save_LDFLAGS=$LDFLAGS
   CFLAGS="$CFLAGS $LTDLINCL"