use CMAKE_* params instead of env vars
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index da302fc..6f3eda0 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -18,7 +18,7 @@
           - name: "Linux / OpenSSL 1.1.1"
             command: make -f misc/docker-ci.mk
           - name: "Linux / OpenSSL 1.1.1 + ASan & UBSan"
-            command: make -f misc/docker-ci.mk CMAKE_ENVS='CC=clang CXX=clang++ CFLAGS="-fsanitize=address,undefined" CXXFLAGS="-fsanitize=address,undefined" LDFLAGS="-fsanitize=address,undefined"' CHECK_ENVS="ASAN_OPTIONS=detect_leaks=0 UBSAN_OPTIONS=print_stacktrace=1"
+            command: make -f misc/docker-ci.mk CMAKE_ARGS='"-DCMAKE_C_COMPILER=clang;-fsanitize=address,undefined" "-DCMAKE_CXX_COMPILER=clang++;-fsanitize=address,undefined"' CHECK_ENVS="ASAN_OPTIONS=detect_leaks=0 UBSAN_OPTIONS=print_stacktrace=1"
 
     timeout-minutes: 10
     steps:
diff --git a/misc/docker-ci.mk b/misc/docker-ci.mk
index cadb1ee..dda5f43 100644
--- a/misc/docker-ci.mk
+++ b/misc/docker-ci.mk
@@ -2,13 +2,12 @@
 SRC_DIR=/quicly
 CI_MK=$(SRC_DIR)/misc/docker-ci.mk
 CMAKE_ARGS=
-CMAKE_ENVS=
 DOCKER_RUN_OPTS=--privileged \
 	-v `pwd`:$(SRC_DIR) \
 	-it
 
 ALL:
-	docker run $(DOCKER_RUN_OPTS) $(CONTAINER_NAME) make -f $(CI_MK) _check CMAKE_ARGS='$(CMAKE_ARGS)' CMAKE_ENVS='$(CMAKE_ENVS)' CHECK_ENVS='$(CHECK_ENVS)'
+	docker run $(DOCKER_RUN_OPTS) $(CONTAINER_NAME) make -f $(CI_MK) _check CMAKE_ARGS='$(CMAKE_ARGS)' CHECK_ENVS='$(CHECK_ENVS)'
 
 _check:
 	uname -a
@@ -16,9 +15,9 @@
 	sudo mount -t tmpfs tmpfs build -o size=3G
 	sudo chown -R ci:ci build
 	sudo chmod 0755 build
-	$(MAKE) -f $(CI_MK) -C build _do-check CMAKE_ARGS='$(CMAKE_ARGS)' CMAKE_ENVS='$(CMAKE_ENVS)' CHECK_ENVS='$(CHECK_ENVS)'
+	$(MAKE) -f $(CI_MK) -C build _do-check CMAKE_ARGS='$(CMAKE_ARGS)' CHECK_ENVS='$(CHECK_ENVS)'
 
 _do-check:
-	env $(CMAKE_ENVS) cmake $(CMAKE_ARGS) -H$(SRC_DIR) -B.
+	cmake $(CMAKE_ARGS) "-H$(SRC_DIR)" -B.
 	make all VERBOSE=1
-	$(CHECK_ENVS) make check
+	env $(CHECK_ENVS) make check