diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
index ffe597abfc..1319ebaf20 100644
--- a/.github/workflows/test.yaml
+++ b/.github/workflows/test.yaml
@@ -103,7 +103,7 @@ jobs:
         timeout-minutes: 1
         run: ${{ env.RUN }} "cd tests/misra && ./test_misra.sh"
       - name: MISRA mutation tests
-        timeout-minutes: 4
+        timeout-minutes: 5
         run: ${{ env.RUN }} "cd tests/misra && pytest -n8 test_mutation.py"
 
   python_linter:
diff --git a/Dockerfile b/Dockerfile
index 63601740e6..ffd5a00a81 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -63,6 +63,8 @@ RUN pyenv install 3.11.4 && \
 ENV CPPCHECK_DIR=/tmp/cppcheck
 COPY tests/misra/install.sh /tmp/
 RUN /tmp/install.sh
+# don't try to install again
+ENV SKIP_CPPCHECK_INSTALL=1
 
 RUN git config --global --add safe.directory /tmp/openpilot/panda
 RUN cd /tmp && \
diff --git a/tests/misra/install.sh b/tests/misra/install.sh
index 6a8a9acb3e..8b264aa61b 100755
--- a/tests/misra/install.sh
+++ b/tests/misra/install.sh
@@ -11,7 +11,6 @@ fi
 cd $CPPCHECK_DIR
 
 VERS="2.13.4"
-git remote prune origin
 git fetch --all --tags
 git checkout $VERS
 git cherry-pick -n f6b538e855f0bacea33c4074664628024ef39dc6 b11b42087ff29569bc3740f5aa07eb6616ea4f63
diff --git a/tests/misra/test_misra.sh b/tests/misra/test_misra.sh
index 482eba2414..982a62e740 100755
--- a/tests/misra/test_misra.sh
+++ b/tests/misra/test_misra.sh
@@ -10,7 +10,7 @@ NC='\033[0m'
 : "${CPPCHECK_DIR:=$DIR/cppcheck/}"
 
 # install cppcheck if missing
-if [ -z "${SKIP_BUILD}" ]; then
+if [ -z "${SKIP_CPPCHECK_INSTALL}" ]; then
   $DIR/install.sh
 fi
 
diff --git a/tests/misra/test_mutation.py b/tests/misra/test_mutation.py
index cf23cf8c65..06ce266e8f 100755
--- a/tests/misra/test_mutation.py
+++ b/tests/misra/test_mutation.py
@@ -21,7 +21,8 @@
   'board/flasher.h',
   'board/bootstub.c',
   'board/bootstub_declarations.h',
-  'board/stm32f4/llflash.h'
+  'board/stm32h7/llflash.h',
+  'board/stm32f4/llflash.h',
 )
 
 mutations = [