diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 8275df7572..fef2f39234 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -125,8 +125,8 @@ Ubuntu_GCC_tests_Debug:
     paths: []
     expire_in: 1 minute
 
-Ubuntu_GCC_Static_Deps:
-  extends: Ubuntu_GCC
+Ubuntu_Static_Deps:
+  extends: Ubuntu_Clang
   rules:
     - if: $CI_PIPELINE_SOURCE == "push"  
       changes:
@@ -136,24 +136,30 @@ Ubuntu_GCC_Static_Deps:
         - ".gitlab-ci.yml"
   allow_failure: true
   cache:
-    key: Ubuntu_GCC_Static_Deps
+    key: Ubuntu_Static_Deps.V1
     paths:
     - apt-cache/
     - ccache/
     - build/extern/fetched/
   before_script:
-    - CI/install_debian_deps.sh gcc openmw-deps openmw-deps-static
+    - CI/install_debian_deps.sh clang openmw-deps openmw-deps-static
   variables:
     CI_OPENMW_USE_STATIC_DEPS: 1
+    CC: clang
+    CXX: clang++
+    CXXFLAGS: -O0
   timeout: 3h
 
-Ubuntu_GCC_Static_Deps_tests:
-  extends: Ubuntu_GCC_Static_Deps
+Ubuntu_Static_Deps_tests:
+  extends: Ubuntu_Static_Deps
   cache:
-    key: Ubuntu_GCC_Static_Deps_tests
+    key: Ubuntu_Static_Deps_tests.V1
   variables:
     CCACHE_SIZE: 1G
     BUILD_TESTS_ONLY: 1
+    CC: clang
+    CXX: clang++
+    CXXFLAGS: -O0
   artifacts:
     paths: []
     expire_in: 1 minute
diff --git a/CI/before_script.linux.sh b/CI/before_script.linux.sh
index 8278ffcd0e..2b1d156c77 100755
--- a/CI/before_script.linux.sh
+++ b/CI/before_script.linux.sh
@@ -17,7 +17,7 @@ fi
 CXX_FLAGS='-Werror -Wno-error=deprecated-declarations -Wno-error=nonnull -Wno-error=deprecated-copy'
 
 if [[ "${CXX}" == 'clang++' ]]; then
-    CXX_FLAGS="${CXX_FLAGS} -Wno-error=unused-lambda-capture -Wno-error=gnu-zero-variadic-macro-arguments"
+    CXX_FLAGS="${CXX_FLAGS} -Wno-error=unused-lambda-capture -Wno-error=gnu-zero-variadic-macro-arguments -Wno-error=misleading-indentation"
 fi
 
 declare -a CMAKE_CONF_OPTS=(
@@ -30,7 +30,7 @@ declare -a CMAKE_CONF_OPTS=(
     -DBUILD_SHARED_LIBS=OFF
     -DUSE_SYSTEM_TINYXML=ON
     -DCMAKE_INSTALL_PREFIX=install
-    -DCMAKE_C_FLAGS='-Werror'
+    -DCMAKE_C_FLAGS="-Werror -Wno-error=misleading-indentation"
     -DCMAKE_CXX_FLAGS="${CXX_FLAGS}"
     -DOPENMW_CXX_FLAGS="-Werror=implicit-fallthrough"
 )
diff --git a/extern/CMakeLists.txt b/extern/CMakeLists.txt
index 0bfdc4c233..27351ce675 100644
--- a/extern/CMakeLists.txt
+++ b/extern/CMakeLists.txt
@@ -147,11 +147,11 @@ if(NOT OPENMW_USE_SYSTEM_OSG)
         endif()
     endif()
 
-    # branch OpenSceneGraph-3.6 on 23 Jan 2021.
+    # OSGoS branch 3.6
     include(FetchContent)
     FetchContent_Declare(osg
-        URL https://github.com/OpenMW/osg/archive/e65f47c4ab3a0b53cc19f517961671e5f840a08d.zip
-        URL_HASH MD5=0c967fe48d80744f6956f6b0b67ef7c6
+        URL https://github.com/OpenMW/osg/archive/01cc2b585c8456a4ff843066b7e1a8715558289f.zip
+        URL_HASH MD5=f1496c5ce32f733581e84568cf2712af
         SOURCE_DIR fetched/osg
     )
     FetchContent_MakeAvailableExcludeFromAll(osg)