diff --git a/source/op/pt/CMakeLists.txt b/source/op/pt/CMakeLists.txt
index 46ea38c193..c7df0d40eb 100644
--- a/source/op/pt/CMakeLists.txt
+++ b/source/op/pt/CMakeLists.txt
@@ -13,6 +13,7 @@ find_package(MPI)
 if(MPI_FOUND)
   target_link_libraries(deepmd_op_pt INTERFACE MPI::MPI_CXX)
   target_compile_definitions(deepmd_op_pt PRIVATE USE_MPI)
+  set(CMAKE_CXX_COMPILER mpicxx)
 endif()
 
 if(CMAKE_TESTING_ENABLED)