diff --git a/Pipfile.lock b/Pipfile.lock
index b3d436d813b662067a8d308744e392889ec9a4a6..8f8390381b5c01609bf0e9620a217327293bfb31 100644
--- a/Pipfile.lock
+++ b/Pipfile.lock
@@ -5,14 +5,14 @@
         },
         "host-environment-markers": {
             "implementation_name": "cpython",
-            "implementation_version": "3.6.2",
+            "implementation_version": "3.6.3",
             "os_name": "posix",
             "platform_machine": "x86_64",
             "platform_python_implementation": "CPython",
             "platform_release": "16.7.0",
             "platform_system": "Darwin",
             "platform_version": "Darwin Kernel Version 16.7.0: Thu Jun 15 17:36:27 PDT 2017; root:xnu-3789.70.16~2/RELEASE_X86_64",
-            "python_full_version": "3.6.2",
+            "python_full_version": "3.6.3",
             "python_version": "3.6",
             "sys_platform": "darwin"
         },
diff --git a/README.md b/README.md
index 4e1bb6fc9cc60a9558df9b5f6f9f1079887f0559..df808ebe5d667d2de7aea58d79a8872a438400d9 100644
--- a/README.md
+++ b/README.md
@@ -23,7 +23,7 @@ Deploying a Python application couldn't be easier:
     $ git push heroku master
     …
     -----> Python app detected
-    -----> Installing python-3.6.2
+    -----> Installing python-3.6.3
     -----> Installing pip
     -----> Installing requirements with latest pipenv…
            ...
@@ -58,7 +58,7 @@ Or, more specifically:
 
 Runtime options include:
 
-- `python-3.6.2`
+- `python-3.6.3`
 - `python-2.7.14`
 - `pypy-5.7.1` (unsupported, experimental)
 - `pypy3-5.5.1` (unsupported, experimental)
diff --git a/bin/compile b/bin/compile
index 4b7682d4d2588177f4b3452ee6ef3676b4a6685b..f43ebf1bc0ece4dcbad61da6e427e65775bd333c 100755
--- a/bin/compile
+++ b/bin/compile
@@ -34,8 +34,8 @@ ENV_DIR=$3
 export BUILD_DIR CACHE_DIR ENV_DIR
 
 # Python defaults
-DEFAULT_PYTHON_VERSION="python-3.6.2"
-LATEST_3="python-3.6.2"
+DEFAULT_PYTHON_VERSION="python-3.6.3"
+LATEST_3="python-3.6.3"
 LATEST_2="python-2.7.14"
 
 DEFAULT_PYTHON_STACK="cedar-14"
diff --git a/bin/steps/pipenv-python-version b/bin/steps/pipenv-python-version
index 361668f2f1df9aa5b414c23cacff75eee1ff0c55..caf11840d558b0455578d8a5fee3f3e81d7723bc 100755
--- a/bin/steps/pipenv-python-version
+++ b/bin/steps/pipenv-python-version
@@ -22,7 +22,7 @@ if [[ -f $BUILD_DIR/Pipfile ]]; then
                     echo "python-2.7.14" > "$BUILD_DIR/runtime.txt"
                 fi
                 if [ "$PYTHON" = 3.6 ]; then
-                    echo "python-3.6.2" > "$BUILD_DIR/runtime.txt"
+                    echo "python-3.6.3" > "$BUILD_DIR/runtime.txt"
                 fi
             fi
 
diff --git a/test/fixtures/pipenv-full-version/Pipfile b/test/fixtures/pipenv-full-version/Pipfile
index 56194d02e060ebc80c4fae6d6a5b85717cb5ed1a..af6f4e4d5e57f295f532325eb3e43f6b045fcb5c 100644
--- a/test/fixtures/pipenv-full-version/Pipfile
+++ b/test/fixtures/pipenv-full-version/Pipfile
@@ -6,4 +6,4 @@ verify_ssl = true
 requests = "*"
 
 [requires]
-python_full_version = "3.6.2"
\ No newline at end of file
+python_full_version = "3.6.3"
\ No newline at end of file
diff --git a/test/fixtures/pipenv-full-version/Pipfile.lock b/test/fixtures/pipenv-full-version/Pipfile.lock
index cdc19c142a2d1c776ec784a57112677c566dbe3c..0a758bdbce9cfc571864b9d5633d490d1f6c0e28 100644
--- a/test/fixtures/pipenv-full-version/Pipfile.lock
+++ b/test/fixtures/pipenv-full-version/Pipfile.lock
@@ -1,24 +1,24 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "8f9e3d5a2863652d7495f17427a33383b3bd9ebd55d331be41fee3cf8631bcd3"
+            "sha256": "22a052f4d1cfe6518b2f236fe45c3208c587a9ab1323bdd390632e27278b541e"
         },
         "host-environment-markers": {
             "implementation_name": "cpython",
-            "implementation_version": "3.6.2",
+            "implementation_version": "3.6.3",
             "os_name": "posix",
             "platform_machine": "x86_64",
             "platform_python_implementation": "CPython",
-            "platform_release": "17.0.0",
+            "platform_release": "16.7.0",
             "platform_system": "Darwin",
-            "platform_version": "Darwin Kernel Version 17.0.0: Thu Aug 24 21:48:19 PDT 2017; root:xnu-4570.1.46~2/RELEASE_X86_64",
-            "python_full_version": "3.6.2",
+            "platform_version": "Darwin Kernel Version 16.7.0: Thu Jun 15 17:36:27 PDT 2017; root:xnu-3789.70.16~2/RELEASE_X86_64",
+            "python_full_version": "3.6.3",
             "python_version": "3.6",
             "sys_platform": "darwin"
         },
         "pipfile-spec": 6,
         "requires": {
-            "python_full_version": "3.6.2"
+            "python_full_version": "3.6.3"
         },
         "sources": [
             {
@@ -30,10 +30,10 @@
     "default": {
         "certifi": {
             "hashes": [
-                "sha256:54a07c09c586b0e4c619f02a5e94e36619da8e2b053e20f594348c0611803704",
-                "sha256:40523d2efb60523e113b44602298f0960e900388cf3bb6043f645cf57ea9e3f5"
+                "sha256:244be0d93b71e93fc0a0a479862051414d0e00e16435707e5bf5000f92e04694",
+                "sha256:5ec74291ca1136b40f0379e1128ff80e866597e4e2c1e755739a913bbc3613c0"
             ],
-            "version": "==2017.7.27.1"
+            "version": "==2017.11.5"
         },
         "chardet": {
             "hashes": [
diff --git a/test/fixtures/pipenv-lock/Pipfile.lock b/test/fixtures/pipenv-lock/Pipfile.lock
index f5414a8e7a2a408093517f7e3bb894ea78df745b..e2ff535ae6c9f9155f5aa163840f35fb1afb3852 100644
--- a/test/fixtures/pipenv-lock/Pipfile.lock
+++ b/test/fixtures/pipenv-lock/Pipfile.lock
@@ -5,14 +5,14 @@
         },
         "host-environment-markers": {
             "implementation_name": "cpython",
-            "implementation_version": "3.6.2",
+            "implementation_version": "3.6.3",
             "os_name": "posix",
             "platform_machine": "x86_64",
             "platform_python_implementation": "CPython",
             "platform_release": "16.7.0",
             "platform_system": "Darwin",
             "platform_version": "Darwin Kernel Version 16.7.0: Thu Jun 15 17:36:27 PDT 2017; root:xnu-3789.70.16~2/RELEASE_X86_64",
-            "python_full_version": "3.6.2",
+            "python_full_version": "3.6.3",
             "python_version": "3.6",
             "sys_platform": "darwin"
         },
diff --git a/test/run b/test/run
index 51db41fccf4f965177b3c24a191bdd22329f7495..8c203d66029f27e559215320fb9bcfa6da20accc 100755
--- a/test/run
+++ b/test/run
@@ -12,13 +12,13 @@ testPipenvLock() {
 
 testPipenvVersion() {
   compile "pipenv-version"
-  assertCaptured "3.6.2"
+  assertCaptured "3.6.3"
   assertCapturedSuccess
 }
 
 testPipenvFullVersion() {
   compile "pipenv-full-version"
-  assertCaptured "3.6.2"
+  assertCaptured "3.6.3"
   assertCapturedSuccess
 }
 
@@ -78,7 +78,7 @@ testPython2() {
 
 testPython3() {
   compile "python3"
-  assertCaptured "python-3.6.2"
+  assertCaptured "python-3.6.3"
   assertCapturedSuccess
 }