diff --git a/config.project b/config.project
index e9a6c6c..051f38d 100644
--- a/config.project
+++ b/config.project
@@ -12,7 +12,7 @@ mb_disable_static=yes
 mb_disable_shared=yes
 
 # custom config step
-mb_use_custom_cfgdefs=no
+mb_use_custom_cfgdefs=yes
 mb_use_custom_cfgtest=no
 
 # pkgconfig
diff --git a/project/config/cfgdefs.sh b/project/config/cfgdefs.sh
new file mode 100644
index 0000000..eb04350
--- /dev/null
+++ b/project/config/cfgdefs.sh
@@ -0,0 +1,46 @@
+for arg ; do
+	case "$arg" in
+		*)
+			error_msg ${arg#}: "unsupported config argument."
+			exit 2
+	esac
+done
+
+cfgdefs_set_arch()
+{
+	if [ -n "$mb_arch" ]; then
+		return 0
+	fi
+
+	case "$mb_cchost" in
+		*-*-*-* )
+			mb_arch=${mb_cchost%-*-*-*}
+			;;
+		*-*-* )
+			mb_arch=${mb_cchost%-*-*}
+			;;
+		*-* )
+			mb_arch=${mb_cchost%-*-*-*}
+			;;
+		* )
+			mb_arch='unknown'
+			;;
+	esac
+
+	if [ "$mb_os" = 'midipix' ]; then
+		case "$mb_arch" in
+			x86_64 )
+				mb_arch='nt64'
+				;;
+			i[3-6]86 )
+				mb_arch='nt32'
+				;;
+		esac
+	fi
+}
+
+# arch
+cfgdefs_set_arch
+
+# all done
+return 0
diff --git a/project/config/cfgdefs.usage b/project/config/cfgdefs.usage
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/project/config/cfgdefs.usage