diff --git a/Dockerfile b/Dockerfile
index d01bdd6..5a642ca 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,14 +1,12 @@
-FROM python:3.5
+FROM pypy:3.5
 RUN apt-get update && \
     apt-get install -y patchelf
-RUN python -m pip install Cython pytest coverage pytest-cov auditwheel doctor-wheel twine
-
-ENV DEBUG=1
+RUN pypy3 -m pip install Cython pytest coverage pytest-cov auditwheel doctor-wheel twine
 
 WORKDIR /tmp/compile
 ADD . /tmp/compile/
 
-RUN python setup.py install && \
+RUN pypy3 setup.py install && \
     chmod ugo+x /tmp/compile/tests/test.sh
 
 CMD ["/tmp/compile/tests/test.sh"]
diff --git a/setup.cfg b/setup.cfg
index fee2bf5..fdc3ec5 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,6 +1,6 @@
 # coding: utf-8
 [metadata]
-version = 2.4a5
+version = 2.4
 name = minijson
 long_description = file: README.md
 long_description_content_type = text/markdown; charset=UTF-8