diff -Naur a/configure.in b/configure.in
--- a/configure.in	2020-03-10 08:02:10.000000000 +0000
+++ b/configure.in	2020-05-16 05:08:34.435771271 +0000
@@ -252,10 +252,10 @@
    epm_scan=\#
    epm_class_driver=
    epm_class_install=yes
-   test `sh ./createPPD.sh -f` == 0
+   test "$(sh ./createPPD.sh -f)" = 0
 else
    AC_MSG_RESULT(no)
-   test `sh ./createPPD.sh -q` == 0
+   test "$(sh ./createPPD.sh -q)" = 0
 fi
 AM_CONDITIONAL(HPLIP_CLASS_DRIVER, test x$class_driver = xyes)