diff --git a/lib/codec_choose.c b/lib/codec_choose.c
index 756f801..0bf8fb6 100644
--- a/lib/codec_choose.c
+++ b/lib/codec_choose.c
@@ -74,7 +74,16 @@
 #define _XCR_XFEATURE_ENABLED_MASK 0
 #endif
 
-#define _XCR_XMM_AND_YMM_STATE_ENABLED_BY_OS 0x6
+#define bit_XMM      (1 << 1)
+#define bit_YMM      (1 << 2)
+#define bit_OPMASK   (1 << 5)
+#define bit_ZMM      (1 << 6)
+#define bit_HIGH_ZMM (1 << 7)
+
+#define _XCR_XMM_AND_YMM_STATE_ENABLED_BY_OS (bit_XMM | bit_YMM)
+
+#define _AVX_512_ENABLED_BY_OS (bit_XMM | bit_YMM | bit_OPMASK | bit_ZMM | bit bit_HIGH_ZMM)
+
 #endif
 
 // Function declarations:
@@ -210,7 +219,7 @@ codec_choose_x86 (struct codec *codec)
 			xcr_mask = _xgetbv(_XCR_XFEATURE_ENABLED_MASK);
 			if ((xcr_mask & _XCR_XMM_AND_YMM_STATE_ENABLED_BY_OS) == _XCR_XMM_AND_YMM_STATE_ENABLED_BY_OS) { // check multiple bits at once
 				#if HAVE_AVX512
-				if (max_level >= 7) {
+				if (max_level >= 7 && ((xcr_mask & _AVX_512_ENABLED_BY_OS) == _AVX_512_ENABLED_BY_OS)) {
 					__cpuid_count(7, 0, eax, ebx, ecx, edx);
 					if ((ebx & bit_AVX512vl) && (ecx & bit_AVX512vbmi)) {
 						codec->enc = base64_stream_encode_avx512;