diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a5e0cf6..b75c0a7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -3,10 +3,8 @@ name: CI
 on:
   push:
     branches: [main]
-    paths-ignore: ['LICENSE', 'README.rst']
   pull_request:
     branches: [main]
-    paths-ignore: ['LICENSE', 'README.rst']
   workflow_dispatch:
 
 env:
@@ -16,34 +14,58 @@ env:
 jobs:
 
   #
-  # Test project on Ubuntu with Intel ifx compiler
+  # Test Fortuno in various system configurations
   #
-  ubuntu-ifx:
-
-    runs-on: ubuntu-latest
+  fortuno-test:
+
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+        toolchain: [Intel, GNU]
+        exclude:
+          - os: macos-latest
+            toolchain: Intel
 
     steps:
 
       - name: Check-out code
         uses: actions/checkout@v3
 
-      - name: Setup Intel oneAPI
+      - name: Setup Intel compiler
+        if: ${{ contains(matrix.toolchain, 'Intel') }}
         uses: rscohn2/setup-oneapi@v0
         with:
           components: ifx
 
-      - name: Set compiler environment
+      - name: Setup Intel environment
+        if: ${{ contains(matrix.toolchain, 'Intel') }}
         run: |
+          source /opt/intel/oneapi/setvars.sh
+          printenv >> ${GITHUB_ENV}
           echo "FC=ifx" >> ${GITHUB_ENV}
           echo "FPM_FC=ifx" >> ${GITHUB_ENV}
 
+      - name: Setup GNU compiler
+        if: ${{ contains(matrix.toolchain, 'GNU') }}
+        uses: fortran-lang/setup-fortran@v1
+        with:
+          compiler: gcc
+          version: 13
+
+      - name: Setup GNU environment
+        if: ${{ contains(matrix.toolchain, 'GNU') }}
+        run: |
+          echo "FC=${{ env.FC }}" >> ${GITHUB_ENV}
+          echo "FPM_FC=${{ env.FC }}" >> ${GITHUB_ENV}
+
       - name: Setup build tools
         run: |
           pip install cmake fpm meson ninja
 
       - name: Build Fortuno
         run: |
-          source /opt/intel/oneapi/setvars.sh
           cmake -B ${BUILD_DIR} -G Ninja -DCMAKE_INSTALL_PREFIX=${INSTALL_DIR}
           cmake --build ${BUILD_DIR}
           cmake --install ${BUILD_DIR}
@@ -51,35 +73,18 @@ jobs:
 
       - name: Test CMake export
         run: |
-          source /opt/intel/oneapi/setvars.sh
           CMAKE_PREFIX_PATH=${INSTALL_DIR} cmake -B ${BUILD_DIR} -G Ninja test/export
           cmake --build ${BUILD_DIR}
           ${BUILD_DIR}/testapp
           rm -rf ${BUILD_DIR}
 
-      - name: Test PkgConfig export
-        run: |
-          source /opt/intel/oneapi/setvars.sh
-          export LD_LIBRARY_PATH="${PWD}/${INSTALL_DIR}/lib:${LD_LIBRARY_PATH}"
-          export PKG_CONFIG_PATH="${PWD}/${INSTALL_DIR}/lib/pkgconfig:${PKG_CONFIG_PATH}"
-          cflags="$(pkg-config --cflags fortuno)"
-          lflags="$(pkg-config --libs fortuno)"
-          mkdir ${BUILD_DIR}
-          pushd ${BUILD_DIR}
-          ifx  ${cflags} ${lflags} -o testapp ../test/export/app/testapp.f90
-          ./testapp
-          popd
-          rm -rf ${BUILD_DIR}
-
       - name: Test fpm export
         run: |
-          source /opt/intel/oneapi/setvars.sh
           cd test/export
           fpm run testapp
 
-      - name: Test meson PkgConfig export
+      - name: Test Meson pkgconfig export
         run: |
-          source /opt/intel/oneapi/setvars.sh
           export PKG_CONFIG_PATH="${PWD}/${INSTALL_DIR}/lib/pkgconfig:${PKG_CONFIG_PATH}"
           cd test/export
           meson setup -Dfortuno_subproject=false ${BUILD_DIR}
@@ -87,9 +92,8 @@ jobs:
           ${BUILD_DIR}/testapp
           rm -rf ./${BUILD_DIR}
 
-      - name: Test meson subproject export
+      - name: Test Meson subproject export
         run: |
-          source /opt/intel/oneapi/setvars.sh
           FORTUNO_DIR=${PWD}
           GIT_REV=$(git rev-parse HEAD)
           cd test/export
diff --git a/README.rst b/README.rst
index dec7b1d..af8b98b 100644
--- a/README.rst
+++ b/README.rst
@@ -227,23 +227,24 @@ detailed explanations, further features and use cases.
 Known issues
 ============
 
-In order to offer a simple user interface, and to be modular, flexible and
-extensible, Fortuno uses modern Fortran constructs extensively. Unfortunately,
-this seems to be still challenging for some Fortran compilers. The following
-table gives an overview over the compilers which were tested for building
-Fortuno.
+In order to offer a simple user interface and to allow for maximal reusability
+and extensibility, Fortuno uses object-oriented Fortran constructs extensively.
+Unfortunately, this is challenging for some older Fortran compilers. The
+following table gives an overview over the compilers which were successfully
+tested for building Fortuno. Make sure to use those compilers or any newer
+versions of them.
 
 +------------------------+-----------------------------------------------------+
 | Compiler               | Status                                              |
 +========================+=====================================================+
 | Intel 2024.0           | * serial: OK                                        |
-| x86_64/Linux           | * mpi (with Intel MPI): OK                          |
+|                        | * mpi: OK                                           |
 +------------------------+-----------------------------------------------------+
 | NAG 7.1 (build 7145)   | * serial: OK                                        |
-| x86_64/Linux           | * mpi (MPICH 4.1): OK                               |
+|                        | * mpi: OK                                           |
 +------------------------+-----------------------------------------------------+
-| GNU 13.2               | * serial: Fails (Internal compiler error)           |
-| x86_64/Linux           |                                                     |
+| GNU 12.2               | * serial: OK                                        |
+|                        | * mpi: OK                                           |
 +------------------------+-----------------------------------------------------+
 
 If you are aware of other compilers being able to build Fortuno, open a pull
diff --git a/src/fortuno/argumentparser.f90 b/src/fortuno/argumentparser.f90
index ce180f4..1c792a8 100644
--- a/src/fortuno/argumentparser.f90
+++ b/src/fortuno/argumentparser.f90
@@ -130,6 +130,8 @@ subroutine argument_parser_parse_args(this, argumentvalues, logger, exitcode)
     allocate(argumentvalues%argvals(0))
     allocate(posargs(0))
     optionsallowed = .true.
+
+    ! Process all arguments
     iarg = 0
     argloop: do while (iarg < nargs)
       iarg = iarg + 1
@@ -183,10 +185,20 @@ subroutine argument_parser_parse_args(this, argumentvalues, logger, exitcode)
         return
       end associate
     end do argloop
+
+    ! Check collected positional arguments
     associate (argdef => this%argdefs(nargdefs))
+      ! If the last argdef was not an option, store all position arguments under this name
       if (.not. allocated(argdef%longopt) .and. argdef%shortopt == "") then
-        argumentvalues%argvals = [argumentvalues%argvals,&
-            & argument_value(name=argdef%name, argval=string_list(posargs))]
+        ! argumentvalues%argvals = [argumentvalues%argvals,&
+        !     & argument_value(name=argdef%name, argval=string_list(posargs))]
+        ! Workaround:gfortran:13.2
+        block
+          class(*), allocatable :: tmp
+          tmp = string_list(posargs)
+          argumentvalues%argvals = [argumentvalues%argvals,&
+              & argument_value(name=argdef%name, argval=tmp)]
+        end block
       else if (size(posargs) > 1) then
         call logger%log_error("Superfluous positional arguments found")
         exitcode = 1