diff --git a/Vagrantfile b/Vagrantfile
index e1dfddd10..209200990 100644
--- a/Vagrantfile
+++ b/Vagrantfile
@@ -3,8 +3,8 @@
 
 # Automated creation of testing environments / binaries on misc. platforms
 
-$cpus = Integer(ENV.fetch('VMCPUS', '4'))  # create VMs with that many cpus
-$xdistn = Integer(ENV.fetch('XDISTN', '4'))  # dispatch tests to that many pytest workers
+$cpus = Integer(ENV.fetch('VMCPUS', '16'))  # create VMs with that many cpus
+$xdistn = Integer(ENV.fetch('XDISTN', '16'))  # dispatch tests to that many pytest workers
 $wmem = $xdistn * 256  # give the VM additional memory for workers [MB]
 
 def packages_debianoid(user)
@@ -160,8 +160,9 @@ end
 def install_pythons(boxname)
   return <<-EOF
     . ~/.bash_profile
-    pyenv install 3.10.2  # tests, version supporting openssl 1.1
-    pyenv install 3.9.13  # tests, version supporting openssl 1.1, binary build
+    pyenv install 3.11.0rc2  # tests
+    pyenv install 3.10.2  # tests
+    pyenv install 3.9.14  # tests, binary build
     pyenv rehash
   EOF
 end
@@ -179,8 +180,8 @@ def build_pyenv_venv(boxname)
     . ~/.bash_profile
     cd /vagrant/borg
     # use the latest 3.9 release
-    pyenv global 3.9.13
-    pyenv virtualenv 3.9.13 borg-env
+    pyenv global 3.9.14
+    pyenv virtualenv 3.9.14 borg-env
     ln -s ~/.pyenv/versions/borg-env .
   EOF
 end
@@ -204,7 +205,7 @@ def install_pyinstaller()
     . ~/.bash_profile
     cd /vagrant/borg
     . borg-env/bin/activate
-    pip install 'pyinstaller==4.10'
+    pip install 'pyinstaller==5.4.1'
   EOF
 end
 
@@ -227,8 +228,8 @@ def run_tests(boxname, skip_env)
     . ../borg-env/bin/activate
     if which pyenv 2> /dev/null; then
       # for testing, use the earliest point releases of the supported python versions:
-      pyenv global 3.9.13 3.10.2
-      pyenv local 3.9.13 3.10.2
+      pyenv global 3.9.14 3.10.2 3.11.0rc2
+      pyenv local 3.9.14 3.10.2 3.11.0rc2
     fi
     # otherwise: just use the system python
     # some OSes can only run specific test envs, e.g. because they miss FUSE support:
diff --git a/src/borg/__main__.py b/src/borg/__main__.py
index 16279fc8d..a561b79b0 100644
--- a/src/borg/__main__.py
+++ b/src/borg/__main__.py
@@ -11,6 +11,7 @@ if sys.platform.startswith("win32"):
     os.environ["PATH"] = os.pathsep.join(dll_path) + os.pathsep + os.environ["PATH"]
 
 
-from .archiver import main
+# note: absolute import from "borg", it seems pyinstaller binaries do not work without this.
+from borg.archiver import main
 
 main()