diff --git a/python-interpreter-builder/Dockerfile.in b/python-interpreter-builder/Dockerfile.in
index 90e606e..3c5fc31 100644
--- a/python-interpreter-builder/Dockerfile.in
+++ b/python-interpreter-builder/Dockerfile.in
@@ -51,10 +51,10 @@ RUN mkdir -p /opt/packages && \
     echo -n "" > /opt/packages/packages.txt
 
 RUN /scripts/build-python-3.5.sh && \
-    /scripts/package-python.sh 3.5.4 "1gcp~${TAG}"
+    /scripts/package-python.sh 3.5.5 "1gcp~${TAG}"
 
 RUN /scripts/build-python-3.6.sh && \
-    /scripts/package-python.sh 3.6.2 "1gcp~${TAG}"
+    /scripts/package-python.sh 3.6.4 "1gcp~${TAG}"
 
 # Tar the interpreters. Tarring is needed because docker cp doesn't handle
 # links correctly.
diff --git a/python-interpreter-builder/scripts/build-python-3.5.sh b/python-interpreter-builder/scripts/build-python-3.5.sh
index eeea1f7..c2a3337 100755
--- a/python-interpreter-builder/scripts/build-python-3.5.sh
+++ b/python-interpreter-builder/scripts/build-python-3.5.sh
@@ -6,14 +6,14 @@ set -x
 # Get the source
 mkdir -p /opt/sources
 cd /opt/sources
-wget --no-verbose https://www.python.org/ftp/python/3.5.4/Python-3.5.4.tgz
+wget --no-verbose https://www.python.org/ftp/python/3.5.5/Python-3.5.5.tgz
 # SHA-256 generated via `shasum -a 256 [file]`
 shasum --check <<EOF
-6ed87a8b6c758cc3299a8b433e8a9a9122054ad5bc8aad43299cff3a53d8ca44  Python-3.5.4.tgz
+2f988db33913dcef17552fd1447b41afb89dbc26e3cdfc068ea6c62013a3a2a5  Python-3.5.5.tgz
 EOF
-tar xzf Python-3.5.4.tgz
+tar xzf Python-3.5.5.tgz
 
-cd Python-3.5.4
+cd Python-3.5.5
 
 # Explanation of flags:
 #
@@ -146,5 +146,5 @@ find "$PREFIX"/lib/python3.5/test \
 
 # Clean-up sources
 cd /opt
-rm /opt/sources/Python-3.5.4.tgz
-rm -r /opt/sources/Python-3.5.4
+rm /opt/sources/Python-3.5.5.tgz
+rm -r /opt/sources/Python-3.5.5
diff --git a/python-interpreter-builder/scripts/build-python-3.6.sh b/python-interpreter-builder/scripts/build-python-3.6.sh
index ca089d5..a61b2a8 100755
--- a/python-interpreter-builder/scripts/build-python-3.6.sh
+++ b/python-interpreter-builder/scripts/build-python-3.6.sh
@@ -6,14 +6,14 @@ set -x
 # Get the source
 mkdir -p /opt/sources
 cd /opt/sources
-wget --no-verbose https://www.python.org/ftp/python/3.6.2/Python-3.6.2.tgz
+wget --no-verbose https://www.python.org/ftp/python/3.6.4/Python-3.6.4.tgz
 # SHA-256 generated via `shasum -a 256 [file]`
 shasum --check <<EOF
-7919489310a5f17f7acbab64d731e46dca0702874840dadce8bd4b2b3b8e7a82  Python-3.6.2.tgz
+7dc453e1a93c083388eb1a23a256862407f8234a96dc4fae0fc7682020227486  Python-3.6.4.tgz
 EOF
-tar xzf Python-3.6.2.tgz
+tar xzf Python-3.6.4.tgz
 
-cd Python-3.6.2
+cd Python-3.6.4
 
 # Explanation of flags:
 #
@@ -146,5 +146,5 @@ find "$PREFIX"/lib/python3.6/test \
 
 # Clean-up sources
 cd /opt
-rm /opt/sources/Python-3.6.2.tgz
-rm -r /opt/sources/Python-3.6.2
+rm /opt/sources/Python-3.6.4.tgz
+rm -r /opt/sources/Python-3.6.4
diff --git a/tests/virtualenv/virtualenv_python35.yaml b/tests/virtualenv/virtualenv_python35.yaml
index 4150ba1..5f37ee5 100644
--- a/tests/virtualenv/virtualenv_python35.yaml
+++ b/tests/virtualenv/virtualenv_python35.yaml
@@ -25,7 +25,7 @@ commandTests:
   - name: "virtualenv35 python version"
     setup: [["virtualenv", "-p", "python3.5", "/env"]]
     command: ["python", "--version"]
-    expectedOutput: ["Python 3.5.4\n"]
+    expectedOutput: ["Python 3.5.5\n"]
 
   - name: "virtualenv35 pip installation"
     setup: [["virtualenv", "-p", "python3.5", "/env"]]
diff --git a/tests/virtualenv/virtualenv_python36.yaml b/tests/virtualenv/virtualenv_python36.yaml
index 71c91a9..132e0fd 100644
--- a/tests/virtualenv/virtualenv_python36.yaml
+++ b/tests/virtualenv/virtualenv_python36.yaml
@@ -25,7 +25,7 @@ commandTests:
   - name: "virtualenv36 python version"
     setup: [["virtualenv", "-p", "python3.6", "/env"]]
     command: ["python", "--version"]
-    expectedOutput: ["Python 3.6.2\n"]
+    expectedOutput: ["Python 3.6.4\n"]
 
   - name: "virtualenv36 pip installation"
     setup: [["virtualenv", "-p", "python3.6", "/env"]]