diff --git a/cmake/cn-gpu.cmake b/cmake/cn-gpu.cmake
index 0e580c565..db60fc0b1 100644
--- a/cmake/cn-gpu.cmake
+++ b/cmake/cn-gpu.cmake
@@ -1,7 +1,10 @@
 if (WITH_CN_GPU)
     set(CN_GPU_SOURCES src/crypto/cn_gpu_avx.cpp src/crypto/cn_gpu_ssse3.cpp)
 
-    if (CMAKE_CXX_COMPILER_ID MATCHES GNU OR CMAKE_CXX_COMPILER_ID MATCHES Clang)
+    if (CMAKE_CXX_COMPILER_ID MATCHES GNU)
+        set_source_files_properties(src/crypto/cn_gpu_avx.cpp PROPERTIES COMPILE_FLAGS "-O3 -mavx2")
+        set_source_files_properties(src/crypto/cn_gpu_ssse3.cpp PROPERTIES COMPILE_FLAGS "-O3")
+    elseif (CMAKE_CXX_COMPILER_ID MATCHES Clang)
         set_source_files_properties(src/crypto/cn_gpu_avx.cpp PROPERTIES COMPILE_FLAGS "-mavx2")
     elseif (CMAKE_CXX_COMPILER_ID MATCHES MSVC)
         set_source_files_properties(src/crypto/cn_gpu_avx.cpp PROPERTIES COMPILE_FLAGS "/arch:AVX")