diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4d592b6d..8bfb78dc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -250,8 +250,8 @@ else()
     endif(OPTIMISE)
 
     # set compiler flags - more are tested and added later
-    set(EXTRA_C_FLAGS "${OPT_C_FLAG} -std=c99 -Wall -Wextra -Wshadow -Wcast-qual -fno-strict-aliasing")
-    set(EXTRA_CXX_FLAGS "${OPT_CXX_FLAG} -std=c++11 -Wall -Wextra -Wshadow -Wswitch -Wreturn-type -Wcast-qual -Wno-deprecated -Wnon-virtual-dtor -fno-strict-aliasing")
+    set(EXTRA_C_FLAGS "${OPT_C_FLAG} -std=c17 -Wall -Wextra -Wshadow -Wcast-qual -fno-strict-aliasing")
+    set(EXTRA_CXX_FLAGS "${OPT_CXX_FLAG} -std=c++17 -Wall -Wextra -Wshadow -Wswitch -Wreturn-type -Wcast-qual -Wno-deprecated -Wnon-virtual-dtor -fno-strict-aliasing")
 
     if (NOT RELEASE_BUILD)
         # -Werror is most useful during development, don't potentially break
diff --git a/cmake/arch.cmake b/cmake/arch.cmake
index c757e91c..15ec067e 100644
--- a/cmake/arch.cmake
+++ b/cmake/arch.cmake
@@ -85,9 +85,9 @@ if (FAT_RUNTIME)
             set (CMAKE_REQUIRED_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_C_FLAGS} ${SKYLAKE_FLAG}")
         endif (BUILD_AVX512VBMI)
     elseif (BUILD_AVX2)
-        set (CMAKE_REQUIRED_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_C_FLAGS} -march=core-avx2")
+        set (CMAKE_REQUIRED_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_C_FLAGS} -march=core-avx2 -mavx")
     elseif ()
-        set (CMAKE_REQUIRED_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_C_FLAGS} -march=core-i7")
+        set (CMAKE_REQUIRED_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_C_FLAGS} -march=core-i7 -mssse3")
     endif ()
 else (NOT FAT_RUNTIME)
     # if not fat runtime, then test given cflags