diff --git a/cmake.deps/cmake/BuildLpeg.cmake b/cmake.deps/cmake/BuildLpeg.cmake
index 81efccf1f4..bbdc83d94d 100644
--- a/cmake.deps/cmake/BuildLpeg.cmake
+++ b/cmake.deps/cmake/BuildLpeg.cmake
@@ -1,4 +1,18 @@
-list(APPEND LPEG_CMAKE_ARGS "-DCMAKE_C_FLAGS:STRING=${DEPS_INCLUDE_FLAGS}")
+set(LPEG_INCLUDE_FLAGS ${DEPS_INCLUDE_FLAGS})
+
+if(NOT USE_BUNDLED_LUAJIT AND NOT USE_BUNDLED_LUA)
+  find_package(Luajit)
+  if(LUAJIT_FOUND)
+    string(CONCAT LPEG_INCLUDE_FLAGS ${DEPS_INCLUDE_FLAGS} " -I${LUAJIT_INCLUDE_DIR}")
+  else()
+    find_package(Lua 5.1 EXACT)
+    if(LUA_FOUND)
+      string(CONCAT LPEG_INCLUDE_FLAGS ${DEPS_INCLUDE_FLAGS} " -I${LUA_INCLUDE_DIR}")
+    endif()
+  endif()
+endif()
+
+list(APPEND LPEG_CMAKE_ARGS -DCMAKE_C_FLAGS=${LPEG_INCLUDE_FLAGS})
 
 ExternalProject_Add(lpeg
   URL ${LPEG_URL}