diff --git a/tools/ci/test_build_system_cmake.sh b/tools/ci/test_build_system_cmake.sh
index 81f00a554..a1be54e4a 100755
--- a/tools/ci/test_build_system_cmake.sh
+++ b/tools/ci/test_build_system_cmake.sh
@@ -592,6 +592,20 @@ endmenu\n" >> ${IDF_PATH}/Kconfig;
         || failure "Version on worktree should have been properly resolved"
     git worktree remove ../esp-idf-template-test
 
+    print_status "Defaults set properly for unspecified idf_build_process args"
+    pushd .
+    cd $IDF_PATH/examples/build_system/cmake/idf_as_lib
+    cp CMakeLists.txt CMakeLists.txt.bak
+    echo -e "\nidf_build_get_property(project_dir PROJECT_DIR)" >> CMakeLists.txt
+    echo -e "\nmessage(\"Project directory: \${project_dir}\")" >> CMakeLists.txt
+    mkdir build && cd build
+    cmake .. -DCMAKE_TOOLCHAIN_FILE=$IDF_PATH/tools/cmake/toolchain-esp32.cmake -DTARGET=esp32 &> log.txt
+    grep "Project directory: $IDF_PATH/examples/build_system/cmake/idf_as_lib" log.txt || failure "PROJECT_DIR default was not set"
+    cd ..
+    mv CMakeLists.txt.bak CMakeLists.txt
+    rm -rf build
+    popd
+
     print_status "All tests completed"
     if [ -n "${FAILURES}" ]; then
         echo "Some failures were detected:"