diff --git a/scripts/config.pl b/scripts/config.pl
index dcebfe62c1..2f4a968ea7 100755
--- a/scripts/config.pl
+++ b/scripts/config.pl
@@ -23,7 +23,7 @@ sub load_config($) {
 			next;
 		};
 		/^# CONFIG_(.+?) is not set/ and do {
-			$config{$1} = -1;
+			$config{$1} = "#undef";
 			next;
 		};
 		/^#/ and next;
@@ -91,7 +91,7 @@ sub config_sub($$) {
 sub print_cfgline($$) {
 	my $name = shift;
 	my $val = shift;
-	if ($val eq '-1') {
+	if ($val eq '#undef') {
 		print "# CONFIG_$name is not set\n";
 	} else {
 		print "CONFIG_$name=$val\n";
diff --git a/target/linux/ixp4xx-2.6/config/default b/target/linux/ixp4xx-2.6/config/default
index 9336723139..7c9fec0d37 100644
--- a/target/linux/ixp4xx-2.6/config/default
+++ b/target/linux/ixp4xx-2.6/config/default
@@ -265,7 +265,7 @@ CONFIG_MTD_PARTITIONS=y
 # CONFIG_MTD_PLATRAM is not set
 # CONFIG_MTD_PMC551 is not set
 # CONFIG_MTD_RAM is not set
-# CONFIG_MTD_REDBOOT_DIRECTORY_BLOCK is not set
+CONFIG_MTD_REDBOOT_DIRECTORY_BLOCK=-1
 CONFIG_MTD_REDBOOT_PARTS=y
 CONFIG_MTD_REDBOOT_PARTS_READONLY=y
 CONFIG_MTD_REDBOOT_PARTS_UNALLOCATED=y
@@ -331,7 +331,6 @@ CONFIG_PATA_ARTOP=m
 # CONFIG_PATA_VIA is not set
 # CONFIG_PATA_WINBOND is not set
 # CONFIG_PC300 is not set
-# CONFIG_PCMCIA is not set
 # CONFIG_PCCARD is not set
 # CONFIG_PCI200SYN is not set
 # CONFIG_PCIPCWATCHDOG is not set