diff --git a/Makefile b/Makefile
index b910a6c8..1a4b44ce 100644
--- a/Makefile
+++ b/Makefile
@@ -1,11 +1,11 @@
 #!/usr/bin/make -f
 
 install-dev-requirements:
-	pip install pipenv==2020.8.13
+	pip install pipenv==2020.11.15
 
 install-test-requirements:
-	pipenv lock -r > requirements.txt
 	pipenv install --dev
+	python -c "import pipfile; pf = pipfile.load('Pipfile'); print('\n'.join(package+version for package, version in pf.data['default'].items()))" > requirements.txt
 
 test-python:
 	@echo "Running Python tests"
diff --git a/Pipfile b/Pipfile
index 1fa0a693..a991f949 100644
--- a/Pipfile
+++ b/Pipfile
@@ -4,11 +4,11 @@ verify_ssl = true
 name = "pypi"
 
 [packages]
-python-magic = "*"
-six = "*"
-decorator = "*"
-urllib3 = "*"
-http-parser = "*"
+python-magic = ">=0.4.5"
+six = ">=1.5.0"
+decorator = ">=4.0.0"
+urllib3 = ">=1.25.3"
+http-parser = ">=0.9.0"
 
 [dev-packages]
 pre-commit = "*"
@@ -23,6 +23,8 @@ pook = "*"
 flake8 = "*"
 twine = "*"
 anaconda-client = "*"
+pipfile = "*"
+wheel = "*"
 
 [requires]
 python_version = "3.8"
diff --git a/mocket/__init__.py b/mocket/__init__.py
index f2f2aa44..e9fde168 100644
--- a/mocket/__init__.py
+++ b/mocket/__init__.py
@@ -7,4 +7,4 @@
 
 __all__ = ("mocketize", "Mocket", "MocketEntry", "Mocketizer")
 
-__version__ = "3.9.3"
+__version__ = "3.9.4"