diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5887c2d45..ffffe911e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -67,6 +67,12 @@ endif()
 set(NTT_UNROOL_NUM 1 CACHE STRING "Set the unroll number for loop unrolling")
 add_compile_definitions(NTT_UNROOL_NUM=${NTT_UNROOL_NUM})
 
+# Workaroud for riscv toolchain auto vectorization bugs in O3
+if (${CMAKE_SYSTEM_PROCESSOR} MATCHES
+   "(riscv32)|(riscv64)")
+    set(CMAKE_CXX_FLAGS_RELEASE "-O2 -DNDEBUG")
+endif()
+
 include(cmake/dependencies.cmake)
 
 set(NNCASE_MAIN_INCLUDE_DIR ${CMAKE_CURRENT_LIST_DIR}/src/Native/include)