diff --git a/.github/workflows/test-exercises.yml b/.github/workflows/test-exercises.yml
index 6df15fd8..61105396 100644
--- a/.github/workflows/test-exercises.yml
+++ b/.github/workflows/test-exercises.yml
@@ -41,13 +41,11 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v6
 
-      - name: Install build dependencies
+      - name: Install test dependencies
         shell: bash
         run: |
           apt-get update
-          apt-get install -y make python3-pip sudo libboost-iostreams-dev libboost-graph-dev
-          mv /usr/local/lib/python3.12/site-packages/* /usr/local/lib/python3.12/dist-packages
-          sudo pip3 install --break-system-packages protobuf==3.20.3 grpcio googleapis-common-protos scapy ptf
+          apt-get install -y make sudo
 
       - name: Run PTF Tests
         run: |
diff --git a/vm-ubuntu-26.04/clean.sh b/vm-ubuntu-26.04/clean.sh
index 6dc3a5be..ed5da21a 100755
--- a/vm-ubuntu-26.04/clean.sh
+++ b/vm-ubuntu-26.04/clean.sh
@@ -28,17 +28,30 @@ cd p4c
 cd ..
 
 /bin/rm usr-local-*.txt pip3-list-2b-*.txt $HOME/.ssh/*
+/bin/rm -fr $HOME/.cache install-details install-p4dev-dumpdir
 
 sudo apt autoremove
 sudo apt clean
 
-# Zero out unused disk blocks.  Results in significantly smaller VM
-# image files.
-
-echo "Writing zeros to unused disk blocks (be patient) ..."
-FNAME="/bigemptyfile"
-sudo dd if=/dev/zero | sudo dd of=${FNAME} bs=4096k
-sudo /bin/rm -f ${FNAME}
+VIRT=`systemd-detect-virt`
+if [ ${VIRT} == "oracle" ]
+then
+    # This is the case if running within VirtualBox.
+    # Zero out unused disk blocks.  Results in significantly smaller VM
+    # image files.
+
+    echo "Writing zeros to unused disk blocks (be patient) ..."
+    FNAME="/bigemptyfile"
+    sudo dd if=/dev/zero | sudo dd of=${FNAME} bs=4096k
+    sudo /bin/rm -f ${FNAME}
+elif [ ${VIRT} == "apple" ]
+then
+    # This is the case if running within UTM on an Apple Silicon Mac
+    # using Apple Virtualization.
+    sudo fstrim -av
+else
+    echo "Unknown output from command systemd-detect-virt: $VIRT"
+fi
 
 echo "Disk usage before running this script:"
 echo "$DF1_BEFORE"