diff --git a/build/global_config.cmake b/build/global_config.cmake
index 3c20af1..af4777a 100755
--- a/build/global_config.cmake
+++ b/build/global_config.cmake
@@ -54,7 +54,7 @@ set(CLANG_FORMAT_FILE "LLVM ${CMAKE_SOURCE_DIR_IPCSDK}/tools/clang-format/.clang
 if(${LINUX_TEST} MATCHES "true")
     set(CLANG_TIDY_SUPPORT                     "true")
     set(CLANG_FORMAT_SUPPORT                   "true")
-    set(LLVM_PATH                              "/home/xiaojiazhu/project/tmp/llvm-project")
+    set(LLVM_PATH                              "${CMAKE_SOURCE_DIR_IPCSDK}/tools/clang-tidy/llvm-project")
 endif()
 # ------------ build clang-tools end ------------ #
 
diff --git a/external/CMakeLists.txt b/external/CMakeLists.txt
index 76688df..959ca0f 100644
--- a/external/CMakeLists.txt
+++ b/external/CMakeLists.txt
@@ -1,5 +1,19 @@
 
 add_subdirectory(sqlite3/sqlite-3430000)
 add_subdirectory(goahead-5.2.0)
+
+find_program(M4 m4)
+if(NOT M4)
+  message("m4 not found. Install before continuing.")
+  execute_process(COMMAND sudo apt-get install m4
+                  WORKING_DIRECTORY ${EXTERNAL_SOURCE_PATH}/gtest/)
+endif()
+find_program(RAGEL ragel)
+if(NOT RAGEL)
+  message(FATAL_ERROR "ragel not found. Install before continuing.")
+  execute_process(COMMAND sudo apt-get install ragel
+                  WORKING_DIRECTORY ${EXTERNAL_SOURCE_PATH}/gtest/)
+endif()
 add_subdirectory(httpserver.h-master/src)
+
 add_subdirectory(cJSON-1.7.17)
\ No newline at end of file