diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6e11ab1..4c05634 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -162,13 +162,13 @@ endif()
 
 if(${ARCH} STREQUAL "x86_64")
   message(STATUS "Detected 64-bit x86 target")
-  #set(CMAKE_CXX_FLAGS "-msse -march=native")
+  #set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -msse -march=native")
 elseif(${ARCH} STREQUAL "ppc64")
   message(STATUS "Detected 64-bit POWER target")
-  set(CMAKE_CXX_FLAGS "-DNO_WARN_X86_INTRINSICS -DSSE_CORRECT_DENORMALS")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DNO_WARN_X86_INTRINSICS -DSSE_CORRECT_DENORMALS")
 elseif(${ARCH} STREQUAL "aarch64")
   message(STATUS "Detected 64-bit ARM target")
-  set(CMAKE_CXX_FLAGS "-DNO_WARN_X86_INTRINSICS -DSSE_CORRECT_DENORMALS")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DNO_WARN_X86_INTRINSICS -DSSE_CORRECT_DENORMALS")
 elseif(${ARCH} STREQUAL "unsupported")
   message(FATAL_ERROR "Unsupported target architecture!  Try porting openEMS to your architecture...")
 else()