diff --git a/config-lib.pl b/config-lib.pl
index 816091d44..2f748e870 100755
--- a/config-lib.pl
+++ b/config-lib.pl
@@ -59,8 +59,8 @@ foreach $o (@lang_order_list) {
 
 # Call any config pre-load function
 if (&foreign_func_exists($module, 'config_pre_load')) {
-	&foreign_call($module, "config_pre_load", \%info, \@info_order)
-	&foreign_call($module, "config_pre_load", \%einfo)
+	&foreign_call($module, "config_pre_load", \%info, \@info_order);
+	&foreign_call($module, "config_pre_load", \%einfo);
 	}
 
 @info_order = &unique(@info_order);
@@ -344,6 +344,20 @@ foreach my $c (@info_order) {
 					    $config->{$c}, @p);
 		}
 	}
+
+# If config fields are conditional (not displayed)
+# make sure to preserve system default values to
+# prevent changing behaviour of a module
+if (&foreign_exists($module) &&
+    &foreign_require($module) &&
+    &foreign_func_exists($module, 'config_preserve')) {
+	my @config_preserve = &foreign_call($module, "config_preserve");
+	my %oldmoduleconf;
+	&read_file("$config_directory/$module/config", \%oldmoduleconf);
+	foreach my $o (@config_preserve) {
+		$config->{$o} = $oldmoduleconf{$o};
+		}
+	}
 }
 
 # config_in_section(&section, &order, &config-info)