diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index c7117fc7..74a6b10d 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -140,6 +140,11 @@ test_ubuntu:
   <<: *ubuntu
   <<: *test_linux
 
+# cpp guideline checks
+test_guidelines:
+  stage: test
+  script:
+    - docker run netgen_${CI_BUILD_REF_NAME}_${UBUNTU_VERSION}.id -e CCACHE_DIR=/ccache -v /mnt/ccache:/ccache netgen_${CI_BUILD_REF_NAME}:${UBUNTU_VERSION} bash /root/src/netgen/tests/build_guidelines.sh
 ############################################
 # Deploy stage
 ############################################
diff --git a/libsrc/core/archive.cpp b/libsrc/core/archive.cpp
index 56bc5426..2e6c32ae 100644
--- a/libsrc/core/archive.cpp
+++ b/libsrc/core/archive.cpp
@@ -24,7 +24,7 @@ namespace ngcore
   void SetLibraryVersion(const std::string& library, const VersionInfo& version)
   { library_versions[library] = version; }
 
-#ifdef WIN
+#ifdef WIN32
   // windows does demangling in typeid(T).name()
   std::string Demangle(const char* typeinfo) { return typeinfo; }
 #else
diff --git a/tests/build.sh b/tests/build.sh
index d2727b2c..68aea3ad 100755
--- a/tests/build.sh
+++ b/tests/build.sh
@@ -1,6 +1,6 @@
 cd
 mkdir -p build/netgen
 cd build/netgen
-cmake ../../src/netgen -DUSE_CCACHE=ON -DENABLE_CPP_CORE_GUIDELINES_CHECK=ON
+cmake ../../src/netgen -DUSE_CCACHE=ON
 make -j12
 make install
diff --git a/tests/build_guidelines.sh b/tests/build_guidelines.sh
new file mode 100644
index 00000000..111b1cd0
--- /dev/null
+++ b/tests/build_guidelines.sh
@@ -0,0 +1,8 @@
+cd
+mkdir -p build/netgen
+cd build/netgen
+cmake ../../src/netgen -DUSE_CCACHE=ON -DENABLE_CPP_CORE_GUIDELINES_CHECK=ON -DCMAKE_CXX_COMPILER=clang++ \
+      -DCMAKE_C_COMPILER=clang
+make -j12
+make install
+
diff --git a/tests/dockerfile b/tests/dockerfile
index 4567fdc4..ebed3dea 100644
--- a/tests/dockerfile
+++ b/tests/dockerfile
@@ -1,5 +1,5 @@
 FROM ubuntu:18.04
 ENV DEBIAN_FRONTEND=noninteractive
 MAINTAINER Matthias Hochsteger <matthias.hochsteger@tuwien.ac.at>
-RUN apt-get update && apt-get -y install python3 libpython3-dev libxmu-dev tk-dev tcl-dev cmake git g++ libglu1-mesa-dev ccache python3-pytest python3-numpy python3-tk clang-tidy python3-distutils
+RUN apt-get update && apt-get -y install python3 libpython3-dev libxmu-dev tk-dev tcl-dev cmake git g++ libglu1-mesa-dev ccache python3-pytest python3-numpy python3-tk clang-tidy python3-distutils clang
 ADD . /root/src/netgen