diff --git a/.github/workflows/docs-ci.yml b/.github/workflows/docs-ci.yml
index 186c3cd8..1279b339 100644
--- a/.github/workflows/docs-ci.yml
+++ b/.github/workflows/docs-ci.yml
@@ -12,11 +12,13 @@ jobs:
         python-version: [3.12]
 
     steps:
-      - name: Checkout code
-        uses: actions/checkout@v4
+      - name: Checkout repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
+        with:
+          persist-credentials: false  # do not keep the token around
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405  # v6.2.0
         with:
           python-version: ${{ matrix.python-version }}
 
diff --git a/.github/workflows/pypi-release.yml b/.github/workflows/pypi-release.yml
index ca12e50b..43a56024 100644
--- a/.github/workflows/pypi-release.yml
+++ b/.github/workflows/pypi-release.yml
@@ -24,9 +24,13 @@ jobs:
     runs-on: ubuntu-24.04
 
     steps:
-      - uses: actions/checkout@v4
-      - name: Set up Python
-        uses: actions/setup-python@v5
+      - name: Checkout repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
+        with:
+          persist-credentials: false  # do not keep the token around
+
+      - name: Set up Python 3.12
+        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405  # v6.2.0
         with:
           python-version: 3.12
 
diff --git a/src/commoncode/system.py b/src/commoncode/system.py
index 3c5a6744..605e09ae 100644
--- a/src/commoncode/system.py
+++ b/src/commoncode/system.py
@@ -30,6 +30,10 @@ def os_arch():
         os = "mac"
     elif "freebsd" in sys_platform:
         os = "freebsd"
+    elif "sunos" in sys_platform:
+        os = "sunos"
+    elif "haiku" in sys_platform:
+        os = "haiku"
     else:
         raise Exception("Unsupported OS/platform %r" % sys_platform)
     return os, arch
@@ -45,7 +49,9 @@ def os_arch():
 on_mac = current_os == "mac"
 on_linux = current_os == "linux"
 on_freebsd = current_os == "freebsd"
-on_posix = not on_windows and (on_mac or on_linux or on_freebsd)
+on_sunos = current_os == "sunos"
+on_haiku = current_os == "haiku"
+on_posix = not on_windows and (on_mac or on_linux or on_freebsd or on_sunos or on_haiku)
 
 current_os_arch = "%(current_os)s-%(current_arch)s" % locals()
 noarch = "noarch"