diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index bf5495742..7fbf0f8a8 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -6,7 +6,7 @@ if (CMAKE_Fortran_COMPILER_ID STREQUAL GNU)
         set(CMAKE_Fortran_FLAGS "${CMAKE_Fortran_FLAGS} -fno-tree-vectorize")
 endif()
 if (CMAKE_Fortran_COMPILER_ID STREQUAL flang)
-	set(CMAKE_Fortran_FLAGS "$CMAKE_Fortran_FLAGS -fno-vectorize -fno-slp-vectorize")
+	set(CMAKE_Fortran_FLAGS "$CMAKE_Fortran_FLAGS -O2")
 endif()
 
 if (BUILD_SINGLE)