diff --git a/contrib/Dockerfile.builder b/contrib/Dockerfile.builder
index e59101da7..9cb430fb8 100644
--- a/contrib/Dockerfile.builder
+++ b/contrib/Dockerfile.builder
@@ -35,4 +35,4 @@ RUN cd /tmp/ && \
     mv /tmp/bitcoin-0.15.1/bin/bitcoin* /usr/local/bin/ && \
     rm -rf bitcoin.tar.gz /tmp/bitcoin-0.15.1
 
-RUN pip3 install python-bitcoinlib==0.7.0 pytest==3.0.5 setuptools==36.6.0 pytest-test-groups==1.0.3
+RUN pip3 install python-bitcoinlib==0.7.0 pytest==3.0.5 setuptools==36.6.0 pytest-test-groups==1.0.3 flake8==3.5.0
diff --git a/contrib/Dockerfile.builder.i386 b/contrib/Dockerfile.builder.i386
index e9d5d7072..2df77d596 100644
--- a/contrib/Dockerfile.builder.i386
+++ b/contrib/Dockerfile.builder.i386
@@ -35,4 +35,4 @@ RUN cd /tmp/ && \
     mv /tmp/bitcoin-0.15.1/bin/bitcoin* /usr/local/bin/ && \
     rm -rf bitcoin.tar.gz /tmp/bitcoin-0.15.1
 
-RUN pip3 install python-bitcoinlib==0.7.0 pytest==3.0.5 setuptools==36.6.0 pytest-test-groups==1.0.3
+RUN pip3 install python-bitcoinlib==0.7.0 pytest==3.0.5 setuptools==36.6.0 pytest-test-groups==1.0.3 flake8==3.5.0