diff --git a/CMakeLists.txt b/CMakeLists.txt
index d5acf8540..755056695 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -343,8 +343,9 @@ if (LLAMA_MPI)
         set(GGML_SOURCES_MPI ggml-mpi.c ggml-mpi.h)
         add_compile_definitions(GGML_USE_MPI)
         add_compile_definitions(${MPI_C_COMPILE_DEFINITIONS})
-        set(cxx_flags ${cxx_flags} -Wno-cast-qual)
-        set(c_flags   ${c_flags}   -Wno-cast-qual)
+        if (NOT MSVC)
+            add_compile_options(-Wno-cast-qual)
+        endif()
         set(LLAMA_EXTRA_LIBS     ${LLAMA_EXTRA_LIBS}     ${MPI_C_LIBRARIES})
         set(LLAMA_EXTRA_INCLUDES ${LLAMA_EXTRA_INCLUDES} ${MPI_C_INCLUDE_DIRS})
         # Even if you're only using the C header, C++ programs may bring in MPI