--- a/configure.ac      2021-12-02 12:37:16.175586192 +0000
+++ b/configure.ac      2021-12-02 12:39:37.346871340 +0000
@@ -248,7 +248,7 @@ if test -z $FLEX; then
    AC_MSG_ERROR([Cannot build utils without flex.])
 fi

-if [[ $WITH_DRBDMON == "yes" ]] ; then
+if test x"$WITH_DRBDMON" = x"yes"; then
    AC_PROG_CXX
    AX_CXX_COMPILE_STDCXX_11(, optional)
    if test "$HAVE_CXX11" = "0"; then