diff --git a/.github/actions/spelling/allow.txt b/.github/actions/spelling/allow.txt
index 846c7874f1..9de0b63b83 100644
--- a/.github/actions/spelling/allow.txt
+++ b/.github/actions/spelling/allow.txt
@@ -2261,3 +2261,4 @@ TESTQUAD
 WAITALL
 xcodebuild
 ICX
+sw_vers
diff --git a/.github/workflows/build_python.yml b/.github/workflows/build_python.yml
index a0ecce12f9..819b3c2cf7 100644
--- a/.github/workflows/build_python.yml
+++ b/.github/workflows/build_python.yml
@@ -26,7 +26,11 @@ jobs:
       fail-fast: false
       matrix:
         # As of 20240501, macos-11/12/13 are AMD64, and macOS-14 is ARM64.
-        os: [ubuntu-20.04, ubuntu-22.04, ubuntu-24.04, windows-2019, windows-2022, macos-11, macos-12, macos-13, macos-14]
+        # As of 20240616, ubuntu 24.04 is failing to copy files into the quay.io/pypa/manylinux2014_i686:2024-05-13-0983f6f container
+        # It fails with "tar: ./todo: Cannot utime: Function not implemented" for every file in the repo.
+        # This is strange since it worked for the quay.io/pypa/manylinux2014_x86_64:2024-05-13-0983f6f container.
+        # I suggest trying ubuntu-24.04 again in a month.
+        os: [ubuntu-20.04, ubuntu-22.04, windows-2019, windows-2022, macos-11, macos-12, macos-13, macos-14]
 
     steps:
       - name: Clone Repository (Latest)
@@ -46,11 +50,27 @@ jobs:
       - name: Checkout pybind11 submodule
         run: git submodule update --init python/pybind11
 
+      # sw_vers on macos 11 and 12 takes -productVersion instead of --productVersion :(
+      - name: Set the MACOSX_DEPLOYMENT_TARGET
+        if: ${{ matrix.os == 'macos-11' || matrix.os == 'macos-12' }}
+        run: |
+          MACOSX_DEPLOYMENT_TARGET=$(sw_vers -productVersion | cut -d'.' -f 1)
+          echo "MACOSX_DEPLOYMENT_TARGET is $MACOSX_DEPLOYMENT_TARGET"
+          echo "MACOSX_DEPLOYMENT_TARGET=$MACOSX_DEPLOYMENT_TARGET" >> $GITHUB_ENV
+
+      - name: Set the MACOSX_DEPLOYMENT_TARGET
+        if: ${{ matrix.os == 'macos-13' || matrix.os == 'macos-14' }}
+        run: |
+          MACOSX_DEPLOYMENT_TARGET=$(sw_vers --productVersion | cut -d'.' -f 1)
+          echo "MACOSX_DEPLOYMENT_TARGET is $MACOSX_DEPLOYMENT_TARGET"
+          echo "MACOSX_DEPLOYMENT_TARGET=$MACOSX_DEPLOYMENT_TARGET" >> $GITHUB_ENV
+
       - name: Set up Fortran
         uses: fortran-lang/setup-fortran@main
         if: ${{ runner.os == 'macOS' }}
         with:
           compiler: gcc
+          version: 12
 
       # Copied from https://github.com/scipy/scipy/blob/main/.github/workflows/wheels.yml
       # For rtools, see https://github.com/r-windows/rtools-installer/releases, which has been
diff --git a/.github/workflows/cmake.yml b/.github/workflows/cmake.yml
index 96c7a59a4c..278e21214d 100644
--- a/.github/workflows/cmake.yml
+++ b/.github/workflows/cmake.yml
@@ -42,7 +42,8 @@ jobs:
         toolchain:
           - {compiler: gcc, version: 11, cflags: '-Wall -Wextra -Wpedantic -Werror', fflags: '-Wall -Wextra -Wpedantic -Werror -fimplicit-none -fcheck=all -fstack-check -Wno-function-elimination'}
           - {compiler: gcc, version: 12, cflags: '-Wall -Wextra -Wpedantic -Werror', fflags: '-Wall -Wextra -Wpedantic -Werror -fimplicit-none -fcheck=all -fstack-check -Wno-function-elimination'}
-          - {compiler: gcc, version: 13, cflags: '-Wall -Wextra -Wpedantic -Werror', fflags: '-Wall -Wextra -Wpedantic -Werror -fimplicit-none -fcheck=all -fstack-check -Wno-function-elimination'}
+          # As of 20240616 gcc13 has issues importing math.h on macOS.
+          # - {compiler: gcc, version: 13, cflags: '-Wall -Wextra -Wpedantic -Werror', fflags: '-Wall -Wextra -Wpedantic -Werror -fimplicit-none -fcheck=all -fstack-check -Wno-function-elimination'}
           - {compiler: intel-classic, version: '2021.8', cflags: '-diag-disable=10441 -Wall -w3 -Werror-all', fflags: '-warn all -debug extended -fimplicit-none -standard-semantics'}
           - {compiler: intel-classic, version: '2021.9', cflags: '-diag-disable=10441 -Wall -w3 -Werror-all', fflags: '-warn all -debug extended -fimplicit-none -standard-semantics'}
           - {compiler: intel-classic, version: '2021.10', cflags: '-diag-disable=10441 -Wall -w3 -Werror-all', fflags: '-warn all -debug extended -fimplicit-none -standard-semantics'}
diff --git a/python/pybind11 b/python/pybind11
index 8a099e44b3..3e9dfa2866 160000
--- a/python/pybind11
+++ b/python/pybind11
@@ -1 +1 @@
-Subproject commit 8a099e44b3d5f85b20f05828d919d2332a8de841
+Subproject commit 3e9dfa2866941655c56877882565e7577de6fc7b
diff --git a/python/tests/test_compatibility_pdfo.py b/python/tests/test_compatibility_pdfo.py
index 6eaaaf6cd5..9ecfc90c06 100644
--- a/python/tests/test_compatibility_pdfo.py
+++ b/python/tests/test_compatibility_pdfo.py
@@ -20,6 +20,9 @@ def test_pdfo():
     scipy = pytest.importorskip("scipy")
     if version.parse(scipy.__version__) < version.parse("1.11.0"):
         pytest.skip("scipy version too old for this test (its version of COBYLA does not accept bounds)")
+    numpy = pytest.importorskip("numpy")
+    if version.parse(numpy.__version__) >= version.parse("2.0.0"):
+        pytest.skip("numpy version too new for this test (pdfo does not yet support numpy v2)")
 
     from pdfo import pdfo
     from scipy.optimize import NonlinearConstraint as NLC, LinearConstraint as LC, Bounds