diff --git a/unittests/ASM/FEX_bugs/cmpxchg_eax.asm b/unittests/ASM/FEX_bugs/cmpxchg_eax.asm
new file mode 100644
index 000000000..9434e2dc7
--- /dev/null
+++ b/unittests/ASM/FEX_bugs/cmpxchg_eax.asm
@@ -0,0 +1,15 @@
+%ifdef CONFIG
+{
+  "RegData": {
+    "RAX": "0x00000000ccddff00",
+    "RBX": "0x8899aabbccddff00"
+  }
+}
+%endif
+
+mov rax, 0x0011223344556677
+mov rbx, 0x8899AABBCCDDFF00
+
+cmpxchg eax, ebx
+
+hlt
\ No newline at end of file