diff --git a/src/config.zig b/src/config.zig
index 46cbfe1..eef7cb8 100644
--- a/src/config.zig
+++ b/src/config.zig
@@ -1 +1,2 @@
 theme: []const u8 = "default",
+include_files: []const u8 = "",
diff --git a/src/config_loader.zig b/src/config_loader.zig
index 040e39b..69f96e1 100644
--- a/src/config_loader.zig
+++ b/src/config_loader.zig
@@ -4,51 +4,153 @@ const builtin = @import("builtin");
 
 const application_name = "flow";
 
-const config = struct {
-    theme: []const u8 = "default",
-};
-
-pub fn read_config(a: std.mem.Allocator, buf: *?[]const u8) config {
-    const file_name = get_app_config_file_name(application_name) catch return .{};
-    return read_json_config_file(a, file_name, buf) catch .{};
+pub fn read_config(T: type, allocator: std.mem.Allocator) struct { T, [][]const u8 } {
+    var bufs: [][]const u8 = &[_][]const u8{};
+    const json_file_name = get_app_config_file_name(application_name, @typeName(T)) catch return .{ .{}, bufs };
+    const text_file_name = json_file_name[0 .. json_file_name.len - ".json".len];
+    var conf: T = .{};
+    if (!read_config_file(T, allocator, &conf, &bufs, text_file_name)) {
+        _ = read_config_file(T, allocator, &conf, &bufs, json_file_name);
+    }
+    read_nested_include_files(T, allocator, &conf, &bufs);
+    return .{ conf, bufs };
 }
 
-fn read_json_config_file(a: std.mem.Allocator, file_name: []const u8, buf: *?[]const u8) !config {
-    var file = std.fs.openFileAbsolute(file_name, .{ .mode = .read_only }) catch |e| switch (e) {
-        error.FileNotFound => return .{},
-        else => return e,
+pub fn free_config(allocator: std.mem.Allocator, bufs: [][]const u8) void {
+    for (bufs) |buf| allocator.free(buf);
+}
+
+// returns true if the file was found
+fn read_config_file(T: type, allocator: std.mem.Allocator, conf: *T, bufs: *[][]const u8, file_name: []const u8) bool {
+    std.log.info("loading {s}", .{file_name});
+    const err: anyerror = blk: {
+        if (std.mem.endsWith(u8, file_name, ".json")) if (read_json_config_file(T, allocator, conf, bufs, file_name)) return true else |e| break :blk e;
+        if (read_text_config_file(T, allocator, conf, bufs, file_name)) return true else |e| break :blk e;
     };
+    switch (err) {
+        error.FileNotFound => return false,
+        else => |e| std.log.err("error reading config file '{s}': {s}", .{ file_name, @errorName(e) }),
+    }
+    return true;
+}
+
+fn read_text_config_file(T: type, allocator: std.mem.Allocator, conf: *T, bufs_: *[][]const u8, file_name: []const u8) !void {
+    var file = try std.fs.openFileAbsolute(file_name, .{ .mode = .read_only });
     defer file.close();
-    const json = try file.readToEndAlloc(a, 64 * 1024);
-    defer a.free(json);
-    const cbor_buf: []u8 = try a.alloc(u8, json.len);
-    buf.* = cbor_buf;
+    const text = try file.readToEndAlloc(allocator, 64 * 1024);
+    defer allocator.free(text);
+    var cbor_buf = std.ArrayList(u8).init(allocator);
+    defer cbor_buf.deinit();
+    const writer = cbor_buf.writer();
+    var it = std.mem.splitScalar(u8, text, '\n');
+    var lineno: u32 = 0;
+    while (it.next()) |line| {
+        lineno += 1;
+        if (line.len == 0 or line[0] == '#')
+            continue;
+        const sep = std.mem.indexOfScalar(u8, line, ' ') orelse {
+            std.log.err("{s}:{}: {s} missing value", .{ file_name, lineno, line });
+            continue;
+        };
+        const name = line[0..sep];
+        const value_str = line[sep + 1 ..];
+        const cb = cbor.fromJsonAlloc(allocator, value_str) catch {
+            std.log.err("{s}:{}: {s} has bad value: {s}", .{ file_name, lineno, name, value_str });
+            continue;
+        };
+        defer allocator.free(cb);
+        try cbor.writeValue(writer, name);
+        try cbor_buf.appendSlice(cb);
+    }
+    const cb = try cbor_buf.toOwnedSlice();
+    var bufs = std.ArrayListUnmanaged([]const u8).fromOwnedSlice(bufs_.*);
+    bufs.append(allocator, cb) catch @panic("OOM:read_text_config_file");
+    bufs_.* = bufs.toOwnedSlice(allocator) catch @panic("OOM:read_text_config_file");
+    return read_cbor_config(T, conf, file_name, cb);
+}
+
+fn read_json_config_file(T: type, allocator: std.mem.Allocator, conf: *T, bufs_: *[][]const u8, file_name: []const u8) !void {
+    var file = try std.fs.openFileAbsolute(file_name, .{ .mode = .read_only });
+    defer file.close();
+    const json = try file.readToEndAlloc(allocator, 64 * 1024);
+    defer allocator.free(json);
+    const cbor_buf: []u8 = try allocator.alloc(u8, json.len);
+    var bufs = std.ArrayListUnmanaged([]const u8).fromOwnedSlice(bufs_.*);
+    bufs.append(allocator, cbor_buf) catch @panic("OOM:read_json_config_file");
+    bufs_.* = bufs.toOwnedSlice(allocator) catch @panic("OOM:read_json_config_file");
     const cb = try cbor.fromJson(json, cbor_buf);
     var iter = cb;
-    var len = try cbor.decodeMapHeader(&iter);
-    var data: config = .{};
-    while (len > 0) : (len -= 1) {
-        var found = false;
-        var field_name: []const u8 = undefined;
-        if (!(try cbor.matchString(&iter, &field_name))) return error.InvalidConfig;
-        inline for (@typeInfo(config).@"struct".fields) |field_info| {
-            if (std.mem.eql(u8, field_name, field_info.name)) {
+    _ = try cbor.decodeMapHeader(&iter);
+    return read_cbor_config(T, conf, file_name, iter);
+}
+
+fn read_cbor_config(
+    T: type,
+    conf: *T,
+    file_name: []const u8,
+    cb: []const u8,
+) !void {
+    var iter = cb;
+    var field_name: []const u8 = undefined;
+    while (cbor.matchString(&iter, &field_name) catch |e| switch (e) {
+        error.TooShort => return,
+        else => return e,
+    }) {
+        var known = false;
+        inline for (@typeInfo(T).@"struct".fields) |field_info|
+            if (comptime std.mem.eql(u8, "include_files", field_info.name)) {
+                if (std.mem.eql(u8, field_name, field_info.name)) {
+                    known = true;
+                    var value: field_info.type = undefined;
+                    if (try cbor.matchValue(&iter, cbor.extract(&value))) {
+                        if (conf.include_files.len > 0) {
+                            std.log.warn("{s}: ignoring nested 'include_files' value '{s}'", .{ file_name, value });
+                        } else {
+                            @field(conf, field_info.name) = value;
+                        }
+                    } else {
+                        try cbor.skipValue(&iter);
+                        std.log.err("invalid value for key '{s}'", .{field_name});
+                    }
+                }
+            } else if (std.mem.eql(u8, field_name, field_info.name)) {
+                known = true;
                 var value: field_info.type = undefined;
-                if (!(try cbor.matchValue(&iter, cbor.extract(&value)))) return error.InvalidConfig;
-                @field(data, field_info.name) = value;
-                found = true;
-            }
+                if (try cbor.matchValue(&iter, cbor.extract(&value))) {
+                    @field(conf, field_info.name) = value;
+                } else {
+                    try cbor.skipValue(&iter);
+                    std.log.err("invalid value for key '{s}'", .{field_name});
+                }
+            };
+        if (!known) {
+            try cbor.skipValue(&iter);
+            std.log.warn("unknown config value '{s}' ignored", .{field_name});
         }
-        if (!found) try cbor.skipValue(&iter);
     }
-    return data;
+}
+
+fn read_nested_include_files(T: type, allocator: std.mem.Allocator, conf: *T, bufs: *[][]const u8) void {
+    if (conf.include_files.len == 0) return;
+    var it = std.mem.splitScalar(u8, conf.include_files, std.fs.path.delimiter);
+    while (it.next()) |path| if (!read_config_file(T, allocator, conf, bufs, path)) {
+        std.log.warn("config include file '{s}' is not found", .{path});
+    };
 }
 
 pub fn get_config_dir() ![]const u8 {
     return get_app_config_dir(application_name);
 }
 
-fn get_app_config_dir(appname: []const u8) ![]const u8 {
+pub const ConfigDirError = error{
+    NoSpaceLeft,
+    MakeConfigDirFailed,
+    MakeHomeConfigDirFailed,
+    MakeAppConfigDirFailed,
+    AppConfigDirUnavailable,
+};
+
+fn get_app_config_dir(appname: []const u8) ConfigDirError![]const u8 {
     const a = std.heap.c_allocator;
     const local = struct {
         var config_dir_buffer: [std.posix.PATH_MAX]u8 = undefined;
@@ -64,7 +166,7 @@ fn get_app_config_dir(appname: []const u8) ![]const u8 {
         const dir = try std.fmt.bufPrint(&local.config_dir_buffer, "{s}/.config", .{home});
         std.fs.makeDirAbsolute(dir) catch |e| switch (e) {
             error.PathAlreadyExists => {},
-            else => return e,
+            else => return error.MakeHomeConfigDirFailed,
         };
         break :ret try std.fmt.bufPrint(&local.config_dir_buffer, "{s}/.config/{s}", .{ home, appname });
     } else if (builtin.os.tag == .windows) ret: {
@@ -73,7 +175,7 @@ fn get_app_config_dir(appname: []const u8) ![]const u8 {
             const dir = try std.fmt.bufPrint(&local.config_dir_buffer, "{s}/{s}", .{ appdata, appname });
             std.fs.makeDirAbsolute(dir) catch |e| switch (e) {
                 error.PathAlreadyExists => {},
-                else => return e,
+                else => return error.MakeAppConfigDirFailed,
             };
             break :ret dir;
         } else return error.AppConfigDirUnavailable;
@@ -82,21 +184,24 @@ fn get_app_config_dir(appname: []const u8) ![]const u8 {
     local.config_dir = config_dir;
     std.fs.makeDirAbsolute(config_dir) catch |e| switch (e) {
         error.PathAlreadyExists => {},
-        else => return e,
+        else => return error.MakeConfigDirFailed,
     };
+
+    var theme_dir_buffer: [std.posix.PATH_MAX]u8 = undefined;
+    std.fs.makeDirAbsolute(try std.fmt.bufPrint(&theme_dir_buffer, "{s}/{s}", .{ config_dir, theme_dir })) catch {};
+
     return config_dir;
 }
 
-fn get_app_config_file_name(appname: []const u8) ![]const u8 {
+const theme_dir = "themes";
+
+fn get_app_config_file_name(appname: []const u8, comptime base_name: []const u8) ConfigDirError![]const u8 {
+    return get_app_config_dir_file_name(appname, base_name ++ ".json");
+}
+
+fn get_app_config_dir_file_name(appname: []const u8, comptime config_file_name: []const u8) ConfigDirError![]const u8 {
     const local = struct {
         var config_file_buffer: [std.posix.PATH_MAX]u8 = undefined;
-        var config_file: ?[]const u8 = null;
     };
-    const config_file_name = "config.json";
-    const config_file = if (local.config_file) |file|
-        file
-    else
-        try std.fmt.bufPrint(&local.config_file_buffer, "{s}/{s}", .{ try get_app_config_dir(appname), config_file_name });
-    local.config_file = config_file;
-    return config_file;
+    return std.fmt.bufPrint(&local.config_file_buffer, "{s}/{s}", .{ try get_app_config_dir(appname), config_file_name });
 }
diff --git a/src/main.zig b/src/main.zig
index 9d4668a..32c819e 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -13,6 +13,11 @@ var lang_override: ?[]const u8 = null;
 var lang_default: []const u8 = "conf";
 const no_highlight = std.math.maxInt(usize);
 
+const builtin = @import("builtin");
+pub const std_options: std.Options = .{
+    .log_level = if (builtin.mode == .Debug) .info else .err,
+};
+
 pub fn main() !void {
     const params = comptime clap.parseParamsComptime(
         \\-h, --help               Display this help and exit.
@@ -72,8 +77,8 @@ pub fn main() !void {
     if (res.args.color == 0 and !stdout_file.supportsAnsiEscapeCodes())
         return plain_cat(res.positionals[0]);
 
-    var conf_buf: ?[]const u8 = null;
-    const conf = config_loader.read_config(a, &conf_buf);
+    const conf, const conf_bufs = config_loader.read_config(a);
+    defer config_loader.free_config(a, conf_bufs);
     const theme_name = if (res.args.theme) |theme| theme else conf.theme;
     const limit_lines = res.args.limit;