diff --git a/unittests/ASM/FEX_bugs/H0F3AREXBug.asm b/unittests/ASM/FEX_bugs/H0F3AREXBug.asm
new file mode 100644
index 0000000000..2f70794333
--- /dev/null
+++ b/unittests/ASM/FEX_bugs/H0F3AREXBug.asm
@@ -0,0 +1,34 @@
+%ifdef CONFIG
+{}
+%endif
+
+; FEX-Emu had a bug in decoding the H0F3A instruction table.
+; It would accidentally require REX.W to not be set on the suite of instructions that ignore the flag.
+; This just executes all instructions from H0F3A that ignore the REX.W flag, to ensure it decodes.
+
+o64 palignr mm0, mm1, 0
+o64 roundps xmm0, xmm1, 0
+o64 roundpd xmm0, xmm1, 0
+o64 roundss xmm0, xmm1, 0
+o64 roundsd xmm0, xmm1, 0
+o64 blendps xmm0, xmm1, 0
+o64 blendpd xmm0, xmm1, 0
+o64 palignr xmm0, xmm1, 0
+o64 pextrb eax, xmm0, 0
+o64 pextrw eax, xmm0, 0
+o64 extractps eax, xmm0, 0
+o64 extractps eax, xmm0, 0
+o64 pinsrb xmm0, eax, 0
+o64 insertps xmm0, xmm1, 0
+o64 dpps xmm0, xmm1, 0
+o64 dppd xmm0, xmm1, 0
+o64 mpsadbw xmm0, xmm1, 0
+o64 pclmulqdq xmm0, xmm1, 0
+o64 pcmpestrm xmm0, xmm1, 0
+o64 pcmpestri xmm0, xmm1, 0
+o64 pcmpistrm xmm0, xmm1, 0
+o64 pcmpistri xmm0, xmm1, 0
+o64 sha1rnds4 xmm0, xmm1, 0
+o64 aeskeygenassist xmm0, xmm1, 0
+
+hlt