--- /dev/null
+--- a/aclocal.in
++++ b/aclocal.in
+@@ -311,7 +311,8 @@ sub scan_m4_dirs ($@)
+ {
+ if (! opendir (DIR, $m4dir))
+ {
+- fatal "couldn't open directory `$m4dir': $!";
++ msg ('override', "warning: skipping not existing directory `$m4dir'");
++ next;
+ }
+
+ # We reverse the directory contents so that foo2.m4 gets