diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 2fa3d75ed..eac564769 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -56,7 +56,7 @@ jobs:
     # github.event.head_commit.message otherwise on pull
     # requests)
     initialize:
-      runs-on: ubuntu-22.04
+      runs-on: ubuntu-24.04
 
       outputs:
         COMMIT_MESSAGE: ${{ steps.setup.outputs.COMMIT_MSG }}
@@ -130,7 +130,7 @@ jobs:
       strategy:
         matrix:
           os:
-            - ubuntu-22.04
+            - ubuntu-24.04
           python-version:
             - 3.9
 
@@ -173,7 +173,7 @@ jobs:
       strategy:
         matrix:
           os:
-            - ubuntu-22.04 # https://github.com/actions/runner-images/blob/main/images/ubuntu/Ubuntu2204-Readme.md
+            - ubuntu-24.04 # https://github.com/actions/runner-images/blob/main/images/ubuntu/Ubuntu2404-Readme.md
             - macos-12 # https://github.com/actions/runner-images/blob/main/images/macos/macos-12-Readme.md
             - macos-14 # https://github.com/actions/runner-images/blob/main/images/macos/macos-14-arm64-Readme.md
             - windows-2019 # https://github.com/actions/runner-images/blob/main/images/windows/Windows2019-Readme.md
@@ -385,7 +385,7 @@ jobs:
       strategy:
         matrix:
           os:
-            - ubuntu-22.04
+            - ubuntu-24.04
           python-version:
             - 3.9
 
@@ -438,7 +438,7 @@ jobs:
       strategy:
         matrix:
           os:
-            - ubuntu-22.04
+            - ubuntu-24.04
             - macos-12
             - macos-14
             - windows-2019
@@ -592,7 +592,7 @@ jobs:
       strategy:
         matrix:
           os:
-            - ubuntu-22.04
+            - ubuntu-24.04
           python-version:
             - 3.9
 
@@ -765,7 +765,7 @@ jobs:
         - test_dependencies
 
       if: startsWith(github.ref, 'refs/tags/v')
-      runs-on: ubuntu-22.04
+      runs-on: ubuntu-24.04
 
       steps:
         - name: Download wheels and sdist
diff --git a/.github/workflows/conda.yml b/.github/workflows/conda.yml
index c64fdb232..903647308 100644
--- a/.github/workflows/conda.yml
+++ b/.github/workflows/conda.yml
@@ -32,7 +32,7 @@ jobs:
       strategy:
         matrix:
           os:
-            - ubuntu-22.04
+            - ubuntu-24.04
             - macos-14
             - macos-12
             - windows-2019
diff --git a/.github/workflows/wiki-lint.yml b/.github/workflows/wiki-lint.yml
index 39c0b859c..c62265462 100644
--- a/.github/workflows/wiki-lint.yml
+++ b/.github/workflows/wiki-lint.yml
@@ -22,7 +22,7 @@ jobs:
     strategy:
       matrix:
         os:
-          - ubuntu-22.04
+          - ubuntu-24.04
         python-version:
           - 3.9
 
diff --git a/cpp/csp/core/Enum.h b/cpp/csp/core/Enum.h
index d6dac5ee9..aac11fd5d 100644
--- a/cpp/csp/core/Enum.h
+++ b/cpp/csp/core/Enum.h
@@ -110,8 +110,8 @@ struct Enum : public EnumTraits
         iterator( int v ) : m_v( v ) {}
 
         Enum operator*() { return Enum( ( EnumV ) m_v ); }
-        bool operator==(const iterator &rhs) { return m_v == rhs.m_v; }
-        bool operator!=(const iterator &rhs) { return !(*this == rhs); }
+        bool operator==(const iterator &rhs) const { return m_v == rhs.m_v; }
+        bool operator!=(const iterator &rhs) const { return !(*this == rhs); }
 
         iterator &operator++() {
             ++m_v;
diff --git a/cpp/csp/cppnodes/statsimpl.h b/cpp/csp/cppnodes/statsimpl.h
index 61cda2346..dc8b9bf96 100644
--- a/cpp/csp/cppnodes/statsimpl.h
+++ b/cpp/csp/cppnodes/statsimpl.h
@@ -1357,7 +1357,7 @@ class Rank
     private:
         ost<std::less<double>> m_mintree;
         ost<std::greater<double>> m_maxtree;
-        double m_lastval;
+        double m_lastval = std::numeric_limits<double>::quiet_NaN();
 
         int64_t m_method;
         int64_t m_nanopt;