diff --git a/build_iso.sh b/build_iso.sh
index 2b4a24f..e018ca3 100755
--- a/build_iso.sh
+++ b/build_iso.sh
@@ -50,10 +50,14 @@ case "${GRML_ISO}" in
     MEMTEST_SCREENSHOT="/code/t/screenshots/01-memtest-v5.jpg"
     echo "*** NOTE: identified Grml ISO ${GRML_ISO}, assuming we have memtest v5"
     ;;
-  *)
+  grml*bookworm*)
     MEMTEST_SCREENSHOT="/code/t/screenshots/01-memtest-v6.jpg"
     echo "*** NOTE: identified Grml ISO ${GRML_ISO}, assuming we have memtest v6"
     ;;
+  *)
+    MEMTEST_SCREENSHOT="/code/t/screenshots/01-memtest-v7.jpg"
+    echo "*** NOTE: identified Grml ISO ${GRML_ISO}, assuming we have memtest v7"
+    ;;
 esac
 
 SCRIPT="$(readlink -f "$0")"
diff --git a/t/Dockerfile b/t/Dockerfile
index b95ac40..0ae001d 100644
--- a/t/Dockerfile
+++ b/t/Dockerfile
@@ -5,7 +5,7 @@ FROM docker.mgm.sipwise.com/sipwise-trixie:latest
 # is updated with the current date. It will force refresh of all
 # of the base images and things like `apt-get update` won't be using
 # old cached versions when the Dockerfile is built.
-ENV REFRESHED_AT=2025-07-21
+ENV REFRESHED_AT=2025-07-22
 
 RUN apt-get update && apt-get install --assume-yes git make gcc dpkg-dev
 
diff --git a/t/iso-tester b/t/iso-tester
index 96a46fe..41f73e1 100755
--- a/t/iso-tester
+++ b/t/iso-tester
@@ -92,7 +92,9 @@ fi
 mkdir -p reports
 if [ -n "${SCREENSHOT_COMPARE:-}" ] ; then
   echo "Comparing ${SCREENSHOT} against ${SCREENSHOT_COMPARE}"
-  if ./screenshot-compare "${SCREENSHOT}" "${SCREENSHOT_COMPARE}" ; then
+  RC=0
+  ./screenshot-compare "${SCREENSHOT}" "${SCREENSHOT_COMPARE}" || RC=$?
+  if [[ "${RC}" -lt 100 ]] ; then
     echo "Looks like ${SCREENSHOT} and ${SCREENSHOT_COMPARE} are looking similar enough."
     echo "1..0" > ./reports/screenshot.tap
   else
diff --git a/t/screenshots/01-memtest-v7.jpg b/t/screenshots/01-memtest-v7.jpg
new file mode 100644
index 0000000..beacc3d
Binary files /dev/null and b/t/screenshots/01-memtest-v7.jpg differ