diff --git a/.github/workflows/macWF.yml b/.github/workflows/macWF.yml
index c6fc3bda30..48be345a1c 100644
--- a/.github/workflows/macWF.yml
+++ b/.github/workflows/macWF.yml
@@ -20,11 +20,10 @@ jobs:
       # see https://github.community/t/how-to-conditionally-include-exclude-items-in-matrix-eg-based-on-branch/16853/6 for possible exclusions
       matrix:
         variant: [ "" , "+allmodules" ]
-        # this is to test both intel and arm64 macs
-        # note: macos-14 has a problem in fetching the git repository of plumed, namely a
-        # "fatal: detected dubious ownership in repository" error
-        # I didn't find any solution, so for the moment I keep macos-14 off
-        os: [ macos-13 ]
+        # macos-15 (arm runner) fails with "Failed to open statefile for plumed:
+        # Could not open file: .../plumed2/plumed2/macports/science/plumed/Portfile"
+        # so we only run on intel macs for now
+        os: [macos-15-intel]
         exclude:
         # many tests on contributed modules are still failing for numerical reasons on arm64, see https://github.com/plumed/plumed2/pull/950
         # once fixed we could introduce this back:
@@ -57,6 +56,12 @@ jobs:
           sudo port -N install $p-plumed
         done
         source ./macports-ci ccache --save
+    - name: show logs
+      if: always()
+      run: |
+        cat /opt/local/var/macports/logs/_Users_runner_work_plumed2_plumed2_macports_science_plumed/plumed/main.log
+        cat /opt/local/var/macports/logs/_Users_runner_work_plumed2_plumed2_macports_python_py-plumed/py39-plumed/main.log
+
     - name: Run tests
       run: |
         sudo port -N -d test plumed ${{ matrix.variant }}
@@ -71,7 +76,7 @@ jobs:
       fail-fast: false
       matrix:
         # this is to test both intel and arm64 macs
-        os: [ macos-13 , macos-14 ]
+        os: [macos-15-intel, macos-15]
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v4
diff --git a/.github/workflows/nightly.yml b/.github/workflows/nightly.yml
index 2bb42a34e8..188ea77702 100644
--- a/.github/workflows/nightly.yml
+++ b/.github/workflows/nightly.yml
@@ -1,5 +1,5 @@
 name: Nightly builds
-on: 
+on:
   schedule:
    - cron: "30 17 * * 0"
 
@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest , macos-13 , macos-14]
+        os: [ubuntu-latest, macos-15-intel, macos-15]
         branch: [v2.8, v2.9, master]
     runs-on: ${{ matrix.os }}
     steps:
diff --git a/macports/.gitignore b/macports/.gitignore
index 5eb6dfb663..c492787462 100644
--- a/macports/.gitignore
+++ b/macports/.gitignore
@@ -1 +1,2 @@
 /science
+/python
diff --git a/macports/generate-portfile.sh b/macports/generate-portfile.sh
index 379647cb64..b6b40595ea 100755
--- a/macports/generate-portfile.sh
+++ b/macports/generate-portfile.sh
@@ -3,6 +3,8 @@
 # This script generates a Portfile in science/plumed
 # Currently the portfile is aimed at testing the currect git hash
 
+alias awk=gawk
+
 prefix=
 if git describe --exact-match --tags HEAD 2>/dev/null 1>/dev/null
 then
@@ -17,11 +19,26 @@ else
 fi
 
 if test -n "$plumed_repository" ; then
-# get this from environment
-  repository="$plumed_repository"
+  fetch="fetch.type          git\n"
+  # get this from environment
+  fetch+="git.url             $plumed_repository\n"
+  # notice that if instead of hashtag we want to put a version, then it should be
+  # git.branch          v${version}
+  fetch+="git.branch          $prefix$version\n"
 else
-# parent directory:
+  # parent directory:
   repository="${PWD%/*}"
+
+  # use a pre-fetch step to copy the sources
+  fetch="fetch.type          none\n\n"
+  fetch+="pre-fetch {\n"
+  fetch+="    ui_msg \"Using local source tree\"\n"
+  fetch+="    set local_repo \"$repository\"\n"
+  fetch+="    system \"rm -rf \${workpath}/localsrc\"\n"
+  fetch+="    system \"cp -a \${local_repo} \${workpath}/localsrc\"\n"
+  fetch+="    return 0\n"
+  fetch+="}\n\n"
+  fetch+="worksrcdir \"\${workpath}/localsrc\"\n"
 fi
 
 mkdir -p science/plumed
@@ -36,15 +53,8 @@ cat Portfile.in |
 sed "
   s/@_VERSION_@/$version/
   s/@_REVISION_@/0/
-" | awk '{
-  if($1=="@_FETCH_@"){
-    print "fetch.type          git"
-    print "git.url             '$repository'"
-# notice that if instead of hashtag we want to put a version, then it should be
-# git.branch          v${version}
-    print "git.branch          '$prefix'${version}"
-  } else print
-}' | awk -v modules="$modules" '{
+  s|@_FETCH_@|$fetch|
+" | awk -v modules="$modules" '{
   if($1=="@_MODULES_@"){
     var=$2
     split(modules,list);
@@ -91,17 +101,5 @@ cat PortfilePython.in |
 sed "
   s/@_VERSION_@/$version/
   s/@_REVISION_@/0/
-" | awk '{
-  if($1=="@_FETCH_@"){
-    print "fetch.type          git"
-    print "git.url             '$repository'"
-# notice that if instead of hashtag we want to put a version, then it should be
-# git.branch          v${version}
-    print "git.branch          '$prefix'${version}"
-  } else print
-}' > python/py-plumed/Portfile
-
-
-
-
-
+  s|@_FETCH_@|$fetch|
+" > python/py-plumed/Portfile