diff --git a/test/misc.cpp b/test/misc.cpp
index 0d79e64..2f0413e 100644
--- a/test/misc.cpp
+++ b/test/misc.cpp
@@ -821,7 +821,9 @@ CYBOZU_TEST_AUTO(vnni)
 	struct Code : Xbyak::CodeGenerator {
 		Code()
 		{
-			vpdpbusd(xm0, xm1, xm2); // EVEX
+			// default encoding is EVEX
+			vpdpbusd(xm0, xm1, xm2);
+			vpdpbusd(xm0, xm1, xm2, EvexEncoding); // EVEX
 			vpdpbusd(xm0, xm1, xm2, VexEncoding); // VEX
 		}
 		void badVex()
@@ -830,6 +832,7 @@ CYBOZU_TEST_AUTO(vnni)
 		}
 	} c;
 	const uint8_t tbl[] = {
+		0x62, 0xF2, 0x75, 0x08, 0x50, 0xC2,
 		0x62, 0xF2, 0x75, 0x08, 0x50, 0xC2,
 		0xC4, 0xE2, 0x71, 0x50, 0xC2,
 	};
diff --git a/xbyak/xbyak.h b/xbyak/xbyak.h
index d60ee8d..9a740b1 100644
--- a/xbyak/xbyak.h
+++ b/xbyak/xbyak.h
@@ -2306,12 +2306,11 @@ private:
 	void opVnni(const Xmm& x1, const Xmm& x2, const Operand& op, int type, int code0, PreferredEncoding encoding)
 	{
 		if (encoding == DefaultEncoding) {
-#ifdef XBYAK_DISABLE_AVX512
-			encoding = VexEncoding;
-#else
 			encoding = EvexEncoding;
-#endif
 		}
+#ifdef XBYAK_DISABLE_AVX512
+		if (encoding == EvexEncoding) XBYAK_THROW(ERR_EVEX_IS_INVALID)
+#endif
 		if (encoding == EvexEncoding) {
 			type |= T_MUST_EVEX;
 		}