diff --git a/src/PVE/SectionConfig.pm b/src/PVE/SectionConfig.pm
index 2b75e6a..5690476 100644
--- a/src/PVE/SectionConfig.pm
+++ b/src/PVE/SectionConfig.pm
@@ -369,17 +369,22 @@ sub parse_config {
 		    my ($k, $v) = ($1, $3);
 
 		    eval {
-			if ($is_array->($type, $k)) {
-			    if (!$unknown) {
-				$v = $plugin->check_value($type, $k, $v, $sectionId);
+			if ($unknown) {
+			    if (!defined($config->{$k})) {
+				$config->{$k} = $v;
+			    } else {
+				if (!ref($config->{$k})) {
+				    $config->{$k} = [$config->{$k}];
+				}
+				push $config->{$k}->@*, $v;
 			    }
+			} elsif ($is_array->($type, $k)) {
+			    $v = $plugin->check_value($type, $k, $v, $sectionId);
 			    $config->{$k} = [] if !defined($config->{$k});
 			    push $config->{$k}->@*, $v;
 			} else {
 			    die "duplicate attribute\n" if defined($config->{$k});
-			    if (!$unknown) {
-				$v = $plugin->check_value($type, $k, $v, $sectionId);
-			    }
+			    $v = $plugin->check_value($type, $k, $v, $sectionId);
 			    $config->{$k} = $v;
 			}
 		    };
@@ -525,7 +530,12 @@ sub write_config {
 		next if defined($done_hash->{$k});
 		$done_hash->{$k} = 1;
 		my $v = $scfg->{$k};
-		$data .= "\t$k $v\n";
+		my $ref = ref($v);
+		if (defined($ref) && $ref eq 'ARRAY') {
+		    $data .= "\t$k $_\n" for $v->@*;
+		} else {
+		    $data .= "\t$k $v\n";
+		}
 	    }
 	    $out .= "$data\n";
 	    next;
diff --git a/test/section_config_test.pl b/test/section_config_test.pl
index 02242bc..ccb364d 100755
--- a/test/section_config_test.pl
+++ b/test/section_config_test.pl
@@ -218,6 +218,7 @@ my $with_unknown_data = {
 	invalid => {
 	    type => 'bad',
 	    common => 'omg',
+	    unknownfield => 'shouldnotbehere',
 	},
     },
     order => enum(qw(t1 t2 invalid t3)),
@@ -234,6 +235,7 @@ one: t2
 
 bad: invalid
 	common omg
+	unknownfield shouldnotbehere
 
 two: t3
 	field2 5