diff --git a/taskcluster/pyenv-win-opt-base.tyml b/taskcluster/pyenv-win-opt-base.tyml
index 8f083581..59c584ba 100644
--- a/taskcluster/pyenv-win-opt-base.tyml
+++ b/taskcluster/pyenv-win-opt-base.tyml
@@ -20,19 +20,21 @@ then:
     mounts:
       - file: msys2-base-x86_64.tar.xz
         content:
-          sha256: 4e799b5c3efcf9efcb84923656b7bcff16f75a666911abd6620ea8e5e1e9870c
+          sha256: c4443113497acb2d2e285d40b929fc55f33f8f669902595ecdf66a655b63dc60
           url: >-
-            https://sourceforge.net/projects/msys2/files/Base/x86_64/msys2-base-x86_64-20180531.tar.xz/download
+            https://github.com/msys2/msys2-installer/releases/download/2020-05-17/msys2-base-x86_64-20200517.tar.xz
 
     env:
-      TC_MSYS_VERSION: 'MSYS_NT-6.3'
+      TC_MSYS_VERSION: 'MSYS_NT-6.3-9600'
       MSYS: 'winsymlinks:nativestrict'
 
     command:
       - >-
         "C:\Program Files\7-zip\7z.exe" x -txz -so msys2-base-x86_64.tar.xz |
         "C:\Program Files\7-zip\7z.exe" x -o%USERPROFILE% -ttar -aoa -si
-      - .\msys64\usr\bin\bash.exe --login -cx "exit"
+      - .\msys64\usr\bin\bash.exe --login -cx "export THIS_BASH_PID=$$; ps -ef | grep '[?]' | awk '{print $2}' | grep -v $THIS_BASH_PID | xargs -r kill; exit 0"
+      - .\msys64\usr\bin\bash.exe --login -cx "pacman -Syu --noconfirm"
+      - .\msys64\usr\bin\bash.exe --login -cx "pacman -Syu --noconfirm"
       - $let:
           taskIndexExpire: { $fromNow: '6 months' }
         in: >
diff --git a/taskcluster/test-win-cuda-opt-base.tyml b/taskcluster/test-win-cuda-opt-base.tyml
index 5fb2c91b..eb2fb1d1 100644
--- a/taskcluster/test-win-cuda-opt-base.tyml
+++ b/taskcluster/test-win-cuda-opt-base.tyml
@@ -30,14 +30,16 @@ then:
         DEEPSPEECH_PROD_MODEL: https://github.com/reuben/DeepSpeech/releases/download/v0.7.0-alpha.3/output_graph.pb
         DEEPSPEECH_PROD_MODEL_MMAP: https://github.com/reuben/DeepSpeech/releases/download/v0.7.0-alpha.3/output_graph.pbmm
         EXPECTED_TENSORFLOW_VERSION: "${build.tensorflow_git_desc}"
-        TC_MSYS_VERSION: 'MSYS_NT-6.3'
+        TC_MSYS_VERSION: 'MSYS_NT-6.3-9600'
         MSYS: 'winsymlinks:nativestrict'
 
     command:
       - >-
         "C:\Program Files\7-zip\7z.exe" x -txz -so msys2-base-x86_64.tar.xz |
         "C:\Program Files\7-zip\7z.exe" x -o%USERPROFILE% -ttar -aoa -si
-      - .\msys64\usr\bin\bash.exe --login -cx "exit"
+      - .\msys64\usr\bin\bash.exe --login -cx "export THIS_BASH_PID=$$; ps -ef | grep '[?]' | awk '{print $2}' | grep -v $THIS_BASH_PID | xargs -r kill; exit 0"
+      - .\msys64\usr\bin\bash.exe --login -cx "pacman -Syu --noconfirm"
+      - .\msys64\usr\bin\bash.exe --login -cx "pacman -Syu --noconfirm"
       - $let:
           extraSystemSetup: { $eval: strip(str(build.system_setup)) }
         in: >
@@ -65,9 +67,9 @@ then:
     mounts:
       - file: msys2-base-x86_64.tar.xz
         content:
-          sha256: 4e799b5c3efcf9efcb84923656b7bcff16f75a666911abd6620ea8e5e1e9870c
+          sha256: c4443113497acb2d2e285d40b929fc55f33f8f669902595ecdf66a655b63dc60
           url: >-
-            https://sourceforge.net/projects/msys2/files/Base/x86_64/msys2-base-x86_64-20180531.tar.xz/download
+            https://github.com/msys2/msys2-installer/releases/download/2020-05-17/msys2-base-x86_64-20200517.tar.xz
       - file: pyenv.tar.gz
         content:
           url: ${system.pyenv.win.url}
diff --git a/taskcluster/test-win-opt-base.tyml b/taskcluster/test-win-opt-base.tyml
index 7171abff..4ddfa595 100644
--- a/taskcluster/test-win-opt-base.tyml
+++ b/taskcluster/test-win-opt-base.tyml
@@ -32,14 +32,16 @@ then:
         DEEPSPEECH_PROD_MODEL: https://github.com/reuben/DeepSpeech/releases/download/v0.7.0-alpha.3/output_graph.pb
         DEEPSPEECH_PROD_MODEL_MMAP: https://github.com/reuben/DeepSpeech/releases/download/v0.7.0-alpha.3/output_graph.pbmm
         EXPECTED_TENSORFLOW_VERSION: "${build.tensorflow_git_desc}"
-        TC_MSYS_VERSION: 'MSYS_NT-6.3'
+        TC_MSYS_VERSION: 'MSYS_NT-6.3-9600'
         MSYS: 'winsymlinks:nativestrict'
 
     command:
       - >-
         "C:\Program Files\7-zip\7z.exe" x -txz -so msys2-base-x86_64.tar.xz |
         "C:\Program Files\7-zip\7z.exe" x -o%USERPROFILE% -ttar -aoa -si
-      - .\msys64\usr\bin\bash.exe --login -cx "exit"
+      - .\msys64\usr\bin\bash.exe --login -cx "export THIS_BASH_PID=$$; ps -ef | grep '[?]' | awk '{print $2}' | grep -v $THIS_BASH_PID | xargs -r kill; exit 0"
+      - .\msys64\usr\bin\bash.exe --login -cx "pacman -Syu --noconfirm"
+      - .\msys64\usr\bin\bash.exe --login -cx "pacman -Syu --noconfirm"
       - $let:
           extraSystemSetup: { $eval: strip(str(build.system_setup)) }
         in: >
@@ -67,9 +69,9 @@ then:
     mounts:
       - file: msys2-base-x86_64.tar.xz
         content:
-          sha256: 4e799b5c3efcf9efcb84923656b7bcff16f75a666911abd6620ea8e5e1e9870c
+          sha256: c4443113497acb2d2e285d40b929fc55f33f8f669902595ecdf66a655b63dc60
           url: >-
-            https://sourceforge.net/projects/msys2/files/Base/x86_64/msys2-base-x86_64-20180531.tar.xz/download
+            https://github.com/msys2/msys2-installer/releases/download/2020-05-17/msys2-base-x86_64-20200517.tar.xz
       - file: pyenv.tar.gz
         content:
           url: ${system.pyenv.win.url}
diff --git a/taskcluster/win-opt-base.tyml b/taskcluster/win-opt-base.tyml
index fa032622..8d77b647 100644
--- a/taskcluster/win-opt-base.tyml
+++ b/taskcluster/win-opt-base.tyml
@@ -30,7 +30,7 @@ payload:
   maxRunTime: { $eval: to_int(build.maxRunTime) }
 
   env:
-    TC_MSYS_VERSION: 'MSYS_NT-6.3'
+    TC_MSYS_VERSION: 'MSYS_NT-6.3-9600'
     MSYS: 'winsymlinks:nativestrict'
     EXAMPLES_CLONE_URL: "https://github.com/mozilla/DeepSpeech-examples"
     EXAMPLES_CHECKOUT_TARGET: "master"
@@ -39,7 +39,9 @@ payload:
     - >-
       "C:\Program Files\7-zip\7z.exe" x -txz -so msys2-base-x86_64.tar.xz |
       "C:\Program Files\7-zip\7z.exe" x -o%USERPROFILE% -ttar -aoa -si
-    - .\msys64\usr\bin\bash.exe --login -cx "exit"
+    - .\msys64\usr\bin\bash.exe --login -cx "export THIS_BASH_PID=$$; ps -ef | grep '[?]' | awk '{print $2}' | grep -v $THIS_BASH_PID | xargs -r kill; exit 0"
+    - .\msys64\usr\bin\bash.exe --login -cx "pacman -Syu --noconfirm"
+    - .\msys64\usr\bin\bash.exe --login -cx "pacman -Syu --noconfirm"
     - echo .\msys64\usr\bin\bash.exe --login -cxe "
       export LC_ALL=C &&
       export PATH=\"/c/builds/tc-workdir/msys64/usr/bin:/c/Python36:/c/Program Files/Git/bin:/c/Program Files/7-Zip/:$PATH\" &&
@@ -71,9 +73,9 @@ payload:
   mounts:
     - file: msys2-base-x86_64.tar.xz
       content:
-        sha256: 4e799b5c3efcf9efcb84923656b7bcff16f75a666911abd6620ea8e5e1e9870c
+        sha256: c4443113497acb2d2e285d40b929fc55f33f8f669902595ecdf66a655b63dc60
         url: >-
-          https://sourceforge.net/projects/msys2/files/Base/x86_64/msys2-base-x86_64-20180531.tar.xz/download
+          https://github.com/msys2/msys2-installer/releases/download/2020-05-17/msys2-base-x86_64-20200517.tar.xz
     - file: home.tar.xz
       content:
         url: ${build.tensorflow}