diff --git a/CMakeLists.txt b/CMakeLists.txt
index cfb1325c..670de51b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -253,6 +253,11 @@ else()
         set(EXTRA_CXX_FLAGS "${EXTRA_CXX_FLAGS} -Wno-abi")
     endif ()
 
+    if (CMAKE_C_COMPILER_ID MATCHES "Intel")
+        set(SKYLAKE_FLAG "-xCORE-AVX512")
+    else ()
+        set(SKYLAKE_FLAG "-march=skylake-avx512")
+    endif ()
 endif()
 
 CHECK_INCLUDE_FILES(unistd.h HAVE_UNISTD_H)
@@ -306,10 +311,6 @@ endif ()
 
 include (${CMAKE_MODULE_PATH}/arch.cmake)
 
-if (NOT FAT_RUNTIME AND NOT HAVE_SSSE3)
-        message(FATAL_ERROR "A minimum of SSSE3 compiler support is required")
-endif ()
-
 # testing a builtin takes a little more work
 CHECK_C_SOURCE_COMPILES("void *aa_test(void *x) { return __builtin_assume_aligned(x, 16);}\nint main(void) { return 0; }" HAVE_CC_BUILTIN_ASSUME_ALIGNED)
 CHECK_CXX_SOURCE_COMPILES("void *aa_test(void *x) { return __builtin_assume_aligned(x, 16);}\nint main(void) { return 0; }" HAVE_CXX_BUILTIN_ASSUME_ALIGNED)
@@ -460,12 +461,6 @@ set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_C_FLAGS}")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${EXTRA_CXX_FLAGS}")
 endif()
 
-if(CMAKE_C_COMPILER_ID MATCHES "Intel")
-    set(SKYLAKE_FLAG "-xCORE-AVX512")
-else()
-    set(SKYLAKE_FLAG "-march=skylake-avx512")
-endif()
-
 if(NOT WIN32)
 set(RAGEL_C_FLAGS "-Wno-unused")
 endif()
diff --git a/cmake/arch.cmake b/cmake/arch.cmake
index 69902f57..0519b2e5 100644
--- a/cmake/arch.cmake
+++ b/cmake/arch.cmake
@@ -10,8 +10,24 @@ else ()
     message (FATAL_ERROR "No intrinsics header found")
 endif ()
 
+if (BUILD_AVX512)
+    CHECK_C_COMPILER_FLAG(${SKYLAKE_FLAG} HAS_ARCH_SKYLAKE)
+    if (NOT HAS_ARCH_SKYLAKE)
+        message (FATAL_ERROR "AVX512 not supported by compiler")
+    endif ()
+endif ()
 
-set (CMAKE_REQUIRED_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_C_FLAGS} ${ARCH_C_FLAGS}")
+if (FAT_RUNTIME)
+    # test the highest level microarch to make sure everything works
+    if (BUILD_AVX512)
+        set (CMAKE_REQUIRED_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_C_FLAGS} ${SKYLAKE_FLAG}")
+    else ()
+        set (CMAKE_REQUIRED_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_C_FLAGS} -march=core-avx2")
+    endif ()
+else (NOT FAT_RUNTIME)
+    # if not fat runtime, then test given cflags
+    set (CMAKE_REQUIRED_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_C_FLAGS} ${ARCH_C_FLAGS}")
+endif ()
 
 # ensure we have the minimum of SSSE3 - call a SSSE3 intrinsic
 CHECK_C_SOURCE_COMPILES("#include <${INTRIN_INC_H}>
@@ -31,10 +47,6 @@ int main(){
     (void)_mm256_xor_si256(z, z);
 }" HAVE_AVX2)
 
-if (NOT HAVE_AVX2)
-    message(STATUS "Building without AVX2 support")
-endif ()
-
 # and now for AVX512
 CHECK_C_SOURCE_COMPILES("#include <${INTRIN_INC_H}>
 #if !defined(__AVX512BW__)
@@ -46,8 +58,27 @@ int main(){
     (void)_mm512_abs_epi8(z);
 }" HAVE_AVX512)
 
-if (NOT HAVE_AVX512)
-    message(STATUS "Building without AVX512 support")
+if (FAT_RUNTIME)
+    if (NOT HAVE_SSSE3)
+        message(FATAL_ERROR "SSSE3 support required to build fat runtime")
+    endif ()
+    if (NOT HAVE_AVX2)
+        message(FATAL_ERROR "AVX2 support required to build fat runtime")
+    endif ()
+    if (BUILD_AVX512 AND NOT HAVE_AVX512)
+        message(FATAL_ERROR "AVX512 support requested but not supported")
+    endif ()
+else (NOT FAT_RUNTIME)
+    if (NOT HAVE_AVX2)
+        message(STATUS "Building without AVX2 support")
+    endif ()
+    if (NOT HAVE_AVX512)
+        message(STATUS "Building without AVX512 support")
+    endif ()
+else (NOT FAT_RUNTIME)
+    if (NOT HAVE_SSSE3)
+        message(FATAL_ERROR "A minimum of SSSE3 compiler support is required")
+    endif ()
 endif ()
 
 unset (CMAKE_REQUIRED_FLAGS)