diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c5a67e5..9658366 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -95,3 +95,37 @@ jobs:
           args: --workspace --no-fail-fast
         env:
           RUST_BACKTRACE: full
+
+  expander_test:
+    strategy:
+      fail-fast: false
+      matrix:
+        toolchain:
+          - 1.42.0-x86_64-unknown-linux-gnu
+          - stable-x86_64-unknown-linux-gnu
+        python-version:
+          - '3.6' # https://packages.ubuntu.com/bionic/python3
+          - '3.8' # https://packages.ubuntu.com/focal/python3
+
+    name: Expand_test (${{ matrix.toolchain }}, ${{ matrix.python-version }})
+    runs-on: ubuntu-18.04
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: 'Setup `${{ matrix.toolchain }}`'
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ matrix.toolchain }}
+          override: true
+          profile: minimal
+          components: rustfmt
+
+      - name: Setup Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: expand.py tests
+        run: bash ./.github/workflows/test-expand.sh
diff --git a/.github/workflows/test-expand.sh b/.github/workflows/test-expand.sh
new file mode 100755
index 0000000..2d5b4c5
--- /dev/null
+++ b/.github/workflows/test-expand.sh
@@ -0,0 +1,22 @@
+#!/bin/bash
+
+TEST_MODULES=(convolution dsu fenwicktree lazysegtree math maxflow mincostflow modint scc segtree string twosat --all)
+TMP_PATH=$(mktemp -d)
+# shellcheck disable=SC2164
+SCRIPT_DIR="$(cd "$(dirname "$0")"; pwd)"
+TEST_FILE="test.rs"
+FILE_HEAD="fn main() {}"
+
+for MODULE in "${TEST_MODULES[@]}" ;do
+     echo Test module "$MODULE"
+     python3 "$SCRIPT_DIR/../../expand.py" "$MODULE" > "$TMP_PATH/$TEST_FILE"
+     echo Output "$(wc -c < "$TMP_PATH/$TEST_FILE")" Bytes
+     echo "$FILE_HEAD" >> "$TMP_PATH/$TEST_FILE"
+     if ! rustc -A warnings "$TMP_PATH/$TEST_FILE";
+     then
+        echo Error compiling for "$MODULE"
+        exit 1
+    else
+        echo Test passed
+     fi
+done
diff --git a/expand.py b/expand.py
new file mode 100755
index 0000000..4072ced
--- /dev/null
+++ b/expand.py
@@ -0,0 +1,118 @@
+#!/usr/bin/python3
+
+import sys
+import getopt
+import tempfile
+import subprocess
+
+usage = '''Usage:expand.py [options] <output modules>
+Output Modules:
+    convolution
+    dsu
+    fenwicktree
+    lazysegtree
+    math
+    maxflow
+    mincostflow
+    modint
+    scc
+    segtree
+    string
+    twosat
+
+You can select multiple modules for <output modules>
+    e.g.)expand.py math segtree
+
+Options:
+    -a  --all       import all modules
+    -h  --help      print help
+'''
+output_header = '//https://github.com/rust-lang-ja/ac-library-rs\n'
+opt_list = ['help', 'all']
+output_list_all = ('convolution', 'dsu', 'fenwicktree', 'lazysegtree', 'math',
+                   'maxflow',  'mincostflow', 'modint', 'scc',  'segtree',
+                   'string', 'twosat',
+                   'internal_bit', 'internal_math', 'internal_queue',
+                   'internal_scc', 'internal_type_traits',)
+dependency_list = {'convolution': ('internal_bit', 'modint',),
+                   'lazysegtree': ('internal_bit', 'segtree'),
+                   'math': ('internal_math',),
+                   'maxflow': ('internal_type_traits', 'internal_queue',),
+                   'mincostflow': ('internal_type_traits',),
+                   'modint': ('internal_math',),
+                   'scc': ('internal_scc',),
+                   'segtree': ('internal_bit', 'internal_type_traits',),
+                   'twosat': ('internal_scc',), }
+src_path = 'src/'
+
+
+def output_file(filename):
+    global src_path
+
+    res = []
+    with open(src_path+filename+'.rs', 'r') as f:
+        res.append('pub mod {} {{'.format(filename))
+
+        for line in f:
+            res.append(line.rstrip())
+
+        res.append('}')
+    return res
+
+
+try:
+    opts, args = getopt.getopt(sys.argv[1:], 'ah', opt_list)
+except getopt.GetoptError as e:
+    print(e)
+    print(usage)
+    sys.exit(2)
+
+if len(opts) == 0 and len(args) == 0:
+    print(usage)
+    sys.exit(0)
+
+for o, v in opts:
+    if o == '--help' or o == '-h':
+        print(usage)
+        sys.exit(0)
+    elif o == '--all' or o == '-a':
+        args = list(output_list_all)
+
+output_list = set()
+
+while len(args) != 0:
+    pop = args.pop()
+    if pop not in output_list_all:
+        print('invalid args:{}'.format(pop))
+        print(usage)
+        sys.exit(2)
+    output_list.add(pop)
+    if pop in dependency_list:
+        for d in dependency_list[pop]:
+            args.append(d)
+
+output_list = list(output_list)
+output_list.sort()
+
+output_data = []
+for i in output_list:
+    buf = output_file(i)
+    output_data.extend(buf)
+
+for i in output_list:
+    # Modules that begin with 'internal' are for internal use, so they are not
+    # declared.
+    if not i.startswith('internal'):
+        output_data.append('use {}::*;'.format(i))
+
+# rustfmt
+with tempfile.TemporaryDirectory() as temp_dir:
+    temp_file = temp_dir + '/output.rs'
+    with open(temp_file, 'w') as f:
+        print(output_header, file=f)
+        for i in output_data:
+            print(i, file=f)
+    output_data = subprocess.run(["rustfmt", temp_file], check=True)
+    with open(temp_file, 'r') as f:
+        for line in f:
+            print(line, end="")