--- 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