diff --git a/.gitignore b/.gitignore
index 894689e..b0ad86d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -91,3 +91,4 @@ ENV/
 doc/_build/*
 *.crt
 .mypy_cache/*
+venv_*/
diff --git a/example/requirements/Makefile b/example/requirements/Makefile
new file mode 100644
index 0000000..81d132e
--- /dev/null
+++ b/example/requirements/Makefile
@@ -0,0 +1,23 @@
+.PHONY: all check clean
+
+
+objects = $(wildcard *.in)
+outputs = $(objects:.in=.txt)
+
+
+all: $(outputs)
+
+
+%.txt: %.in
+	pip-compile -v -U --output-file $@ $<
+
+
+develop.txt: base.txt
+
+
+check:
+	@which pip-compile > /dev/null
+
+
+clean:
+	-rm *.txt
diff --git a/example/requirements.in b/example/requirements/base.in
similarity index 100%
rename from example/requirements.in
rename to example/requirements/base.in
diff --git a/example/requirements.txt b/example/requirements/base.txt
similarity index 64%
rename from example/requirements.txt
rename to example/requirements/base.txt
index 6020bbb..8ef4c22 100644
--- a/example/requirements.txt
+++ b/example/requirements/base.txt
@@ -2,24 +2,25 @@
 # This file is autogenerated by pip-compile
 # To update, run:
 #
-#    pip-compile --output-file requirements.txt requirements.in
+#    pip-compile --output-file base.txt base.in
 #
 click==6.7                # via flask
 dominate==2.3.1           # via flask-bootstrap
 enum-compat==0.0.2        # via eventlet
+enum34==1.1.6             # via enum-compat
 eventlet==0.21.0
 flask-bootstrap==3.3.7.1
-flask-mqtt==0.0.4
+flask-mqtt==0.0.5
 flask-socketio==2.8.6
-flask==0.12.1
+flask==0.12.2
 greenlet==0.4.12          # via eventlet
 itsdangerous==0.24        # via flask
 jinja2==2.9.6             # via flask
 markupsafe==1.0           # via jinja2
-paho-mqtt==1.2.3          # via flask-mqtt
-python-engineio==1.3.2    # via flask-socketio, python-socketio
-python-socketio==1.7.4    # via flask-socketio
+paho-mqtt==1.3.0          # via flask-mqtt
+python-engineio==1.5.4    # via flask-socketio, python-socketio
+python-socketio==1.7.5    # via flask-socketio
 six==1.10.0               # via python-engineio, python-socketio
 typing==3.6.1             # via flask-mqtt
 visitor==0.1.3            # via flask-bootstrap
-werkzeug==0.12.1          # via flask
+werkzeug==0.12.2          # via flask
diff --git a/example/requirements/develop.in b/example/requirements/develop.in
new file mode 100644
index 0000000..29e7210
--- /dev/null
+++ b/example/requirements/develop.in
@@ -0,0 +1,2 @@
+-r base.txt
+pip-tools
diff --git a/example/requirements/develop.txt b/example/requirements/develop.txt
new file mode 100644
index 0000000..5b9add5
--- /dev/null
+++ b/example/requirements/develop.txt
@@ -0,0 +1,28 @@
+#
+# This file is autogenerated by pip-compile
+# To update, run:
+#
+#    pip-compile --output-file develop.txt develop.in
+#
+click==6.7
+dominate==2.3.1
+enum-compat==0.0.2
+enum34==1.1.6
+eventlet==0.21.0
+first==2.0.1              # via pip-tools
+flask-bootstrap==3.3.7.1
+flask-mqtt==0.0.5
+flask-socketio==2.8.6
+flask==0.12.2
+greenlet==0.4.12
+itsdangerous==0.24
+jinja2==2.9.6
+markupsafe==1.0
+paho-mqtt==1.3.0
+pip-tools==1.9.0
+python-engineio==1.5.4
+python-socketio==1.7.5
+six==1.10.0
+typing==3.6.1
+visitor==0.1.3
+werkzeug==0.12.2