diff --git a/src/gpg-error-config-main.sh b/src/gpg-error-config-main.sh
index 37eb193..d7b9c56 100644
--- a/src/gpg-error-config-main.sh
+++ b/src/gpg-error-config-main.sh
@@ -1,108 +1,123 @@
 
 if echo "$0" | grep gpg-error-config 2>/dev/null >/dev/null; then
   myname="gpg-error-config"
 else
   myname="gpgrt-config"
 fi
 
 usage()
 {
     cat <<EOF
 Usage: $myname [OPTIONS]
 Options:
         [--mt]       (must be the first option)
 	[--prefix]
 	[--exec-prefix]
 	[--version]
 	[--libs]
 	[--cflags]
 EOF
     exit $1
 }
 
 if test $# -eq 0; then
     usage 1 1>&2
 fi
 
 if [ "$1" != "--mt" ]; then
     mt=no
 else
     # In future, use --variable=mtcflags or --variable=mtlibs
     mt=yes
     shift
 fi
 
 read_config_file ${myname%-config} $PKG_CONFIG_PATH
 
 opt_cflags=no
 opt_libs=no
 output=""
 
 while test $# -gt 0; do
     case "$1" in
 	-*=*)
 	    optarg=`echo "$1" | sed 's/[-_a-zA-Z0-9]*=//'`
 	    ;;
 	*)
 	    optarg=
 	    ;;
     esac
 
     case $1 in
 	--prefix)
 	    # In future, use --variable=prefix instead.
 	    output="$output $(get_var prefix)"
 	    ;;
 	--exec-prefix)
 	    # In future, use --variable=exec_prefix instead.
 	    output="$output $(get_var exec_prefix)"
 	    ;;
 	--version)
 	    # In future, use --modversion instead.
 	    echo "$(get_attr Version)"
 	    exit 0
 	    ;;
 	--modversion)
 	    echo "$(get_attr Version)"
 	    exit 0
 	    ;;
 	--cflags)
 	    opt_cflags=yes
 	    ;;
 	--libs)
 	    opt_libs=yes
 	    ;;
 	--variable=*)
 	    echo "$(get_var ${1#*=})"
 	    exit 0
 	    ;;
 	--host)
 	    # In future, use --variable=host instead.
 	    echo "$(get_var host)"
 	    exit 0
 	    ;;
 	*)
 	    usage 1 1>&2
 	    ;;
     esac
     shift
 done
 
-if [ opt_cflags = yes ]; then
-    output="$output $(get_attr Cflags)"
+cflags="$(get_attr Cflags)"
+libs="$(get_attr Libs)"
+
+mtcflags="$(get_var mtcflags)"
+mtlibs="$(get_var mtlibs)"
+
+requires="$(get_attr Requires)"
+cleanup_vars_attrs
+pkg_list=$(all_required_config_files $requires)
+
+for p in $pkg_list; do
+    read_config_file $p $PKG_CONFIG_PATH
+    cflags="$cflags $(get_attr Cflags)"
+    libs="$libs $(get_attr Libs)"
+    cleanup_vars_attrs
+done
+
+if [ $opt_cflags = yes ]; then
+    output="$output $cflags"
     # Backward compatibility to old gpg-error-config
     if [ $mt = yes ]; then
-	output="$output $(get_var mtcflags)"
+	output="$output $mtcflags"
     fi
 fi
-if [ opt_libs = yes ]; then
-    output="$output $(get_attr Libs)"
+if [ $opt_libs = yes ]; then
+    output="$output $libs"
     # Backward compatibility to old gpg-error-config
     if [ $mt = yes ]; then
-	output="$output $(get_var mtlibs)"
+	output="$output $mtlibs"
     fi
 fi
 
-# cleanup_vars_attrs
-
 echo $output
diff --git a/src/pkgconf-funcs.sh b/src/pkgconf-funcs.sh
index 38dccf0..a51a8c3 100644
--- a/src/pkgconf-funcs.sh
+++ b/src/pkgconf-funcs.sh
@@ -1,138 +1,191 @@
 #### start of pkgconf-funcs
 
 #
 # Bourne shell functions for config file in pkg-config style, so that
 # we can share such a config file between pkg-config and script
 #
 
 #
 # get_var: Get the variable value of NAME
 #
 # Variables are recorded in the shell variables named "VAR_<NAME>"
 #
 get_var () {
     local name=$1
 
     eval echo \$VAR_$name
 }
 
 #
 # get_attr: Get the attribute value of KEY
 #
 # Attributes are recorded in the shell variables named "ATTR_<KEY>"
 #
 get_attr () {
     local name=$1
 
     eval echo \$ATTR_$name
 }
 
 # Remove ${varname} part in the beginning of a string.
 remove_var_expr () {
     local varname=$1
     shift
 
     eval echo \"\${@#\\\$\\\{$varname\\\}}\"
 }
 
 # Given a string, substitute variables.
 substitute_vars () {
     local string="$1"
     local line
     local varname
     local result
 
     while [ -n "$string" ]; do
 	case "$string" in
 	    \$\$*)
 		result="$result\$"
 		string="${string#\$\$}"
 		;;
 	    \${*}*)
 		varname="${string#\$\{}"
 		varname="${varname%%\}*}"
 		result="$result$(get_var ${varname})"
 		string=$(remove_var_expr ${varname} ${string})
 		;;
 	    *)
 		result="${result}$(printf %c "$string")"
 		string="${string#$(printf %c "$string")}"
 		;;
 	esac
     done
 
     echo "$result"
 }
 
 #
 # Read a config from stdin
 #
 # Variables:
 # For VAR=VALUE, value is stored in the shell variable VAR_*.
 #
 # Attributes:
 # For KEY: VALUE, value is stored in the shell variable ATTR_*.
 #
 read_config_from_stdin () {
     local line
     local varname
     local value
     local key
 
     while read line; do
 	case "$line" in
 	    *=*)
 		varname="${line%%=*}"
 		value="${line#*=}"
 		VAR_list="$VAR_list VAR_$varname"
 		read VAR_$varname <<EOF1
 $(substitute_vars "$value")
 EOF1
 		;;
 	    *:\ *)
 		key="${line%%:\ *}"
 		value="${line#*:\ }"
 		ATTR_list="$ATTR_list ATTR_$key"
 		read ATTR_$key <<EOF2
 $(substitute_vars "$value")
 EOF2
 		;;
 	esac
     done
 }
 
 
 find_file_in_path () {
     local f=$1
     local p=$2
     local IFS=":"		# On Windows it should be ";"???
 
     for d in $p; do
 	if [ -r $d/$f ]; then
 	    RESULT="$d/$f"
 	    return 0
 	fi
     done
     RESULT=""
     return 1
 }
 
 read_config_file () {
     local config_file
     local RESULT
 
     if find_file_in_path $1.pc $2; then
 	config_file=$RESULT
     else
 	echo "Can't find $1.pc" 1>&2
 	exit 1
     fi
     read_config_from_stdin < $config_file
 }
 
 cleanup_vars_attrs () {
     eval unset $VAR_list VAR_list
     eval unset $ATTR_list ATTR_list
 }
 
+not_listed_yet () {
+    local m=$1
+    shift
+
+    for arg; do
+	if [ $m = $arg ]; then
+	    return 1
+	fi
+    done
+
+    return 0
+}
+
+list_only_once () {
+    local result=""
+    local arg
+
+    for arg; do
+	if not_listed_yet $arg "$result"; then
+	    result="$result $arg"
+	fi
+    done
+
+    echo $result
+}
+
+#
+# Recursively solve package dependencies
+#
+# XXX: version requirement (version comparison) is not yet supported
+#
+all_required_config_files () {
+    local list="$1"
+    local all_list
+    local new_list
+    local p
+
+    all_list="$list"
+
+    while [ -n "$list" ]; do
+	new_list=""
+	for p in $list; do
+	    read_config_file $p $PKG_CONFIG_PATH
+	    new_list="$new_list $(get_attr Requires)"
+	    cleanup_vars_attrs
+	done
+	all_list="$all_list $new_list"
+	list="$new_list"
+    done
+
+    echo $(list_only_once $all_list)
+}
+
 #### end of pkgconf-funcs