diff --git a/.github/workflows/gfortran.yml b/.github/workflows/gfortran.yml
index e4ab7adb..5a575a1f 100644
--- a/.github/workflows/gfortran.yml
+++ b/.github/workflows/gfortran.yml
@@ -34,11 +34,15 @@ jobs:
 
   basic_build:
     name: Basic build
-    runs-on: ubuntu-22.04
+    runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
       matrix:
-         gcc_v: [9, 12]
+         os: [ubuntu-22.04]
+         gcc_v: [9, 13]
+         include:
+          - os: macos-14
+            gcc_v: 13
     env:
       FC: gfortran
       GCC_V: ${{ matrix.gcc_v}}
@@ -49,11 +53,10 @@ jobs:
       with:
         fetch-depth: 2
 
-    - name: Set GFortran version
-      run: |
-        sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-${GCC_V} 100 \
-        --slave /usr/bin/gfortran gfortran /usr/bin/gfortran-${GCC_V} \
-        --slave /usr/bin/gcov gcov /usr/bin/gcov-${GCC_V}
+    - uses: fortran-lang/setup-fortran@v1
+      with:
+        compiler: gcc
+        version: ${{ matrix.gcc_v }}
 
     # pFUnit library is used to build and run unit tests
     - name: pFUnit build Cache
diff --git a/dev_scripts/install_pfunit.sh b/dev_scripts/install_pfunit.sh
index 1221c32b..e516d564 100755
--- a/dev_scripts/install_pfunit.sh
+++ b/dev_scripts/install_pfunit.sh
@@ -17,7 +17,7 @@ git clone --recursive https://github.com/Goddard-Fortran-Ecosystem/pFUnit $REPO_
 
 # This seems to be the last commit that works with GCC-7
 # Later commits fail with internal compiler error when compiling fArgParse submodule. 
-git checkout --recurse-submodules 0a09db354b665f1518e36460396c348c19185e04
+#git checkout --recurse-submodules 0a09db354b665f1518e36460396c348c19185e04
 
 mkdir -p build && cd build
 export FC=gfortran
diff --git a/tests/numdiff.py b/tests/numdiff.py
index 496074d3..9c1f14b6 100755
--- a/tests/numdiff.py
+++ b/tests/numdiff.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 import argparse
 import decimal
 import os.path
diff --git a/tests/test.sh b/tests/test.sh
index 77a6530b..cb73dd0d 100755
--- a/tests/test.sh
+++ b/tests/test.sh
@@ -1,6 +1,14 @@
 #!/bin/bash
+
+# Stop on any error
 set -euo pipefail
 
+# Make sure that '[A-Z]' regex works as expected,
+# i.e. only matches capital letters, regardless of global collate settings.
+# This workaround is needed for MacOS 15,
+# but is probably a good idea in general to make this script robust.
+export LC_ALL=C
+
 # Parameters are passed from Makefile.
 if [[ $# -ne 8 ]]; then
   echo "ERROR: Incorrect number of parameters passed to $0"