Index: /trunk/src/VBox/VMM/VMMAll/IEMAll.cpp
===================================================================
--- /trunk/src/VBox/VMM/VMMAll/IEMAll.cpp	(revision 40380)
+++ /trunk/src/VBox/VMM/VMMAll/IEMAll.cpp	(revision 40381)
@@ -6213,5 +6213,5 @@
 #define IEM_MC_STORE_MEM_NEG_QNAN_R80_BY_REF(a_pr80Dst) \
     do { \
-        (a_pr80Dst)->au64[1] = UINT64_C(0xc000000000000000); \
+        (a_pr80Dst)->au64[0] = UINT64_C(0xc000000000000000); \
         (a_pr80Dst)->au16[4] = UINT16_C(0xffff); \
     } while (0)