diff --git a/target-i386/cpuid.c b/target-i386/cpuid.c
index 5382a28..28275a6 100644
--- a/target-i386/cpuid.c
+++ b/target-i386/cpuid.c
@@ -1104,7 +1104,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
         /* mwait info: needed for Core compatibility */
         *eax = 0; /* Smallest monitor-line size in bytes */
         *ebx = 0; /* Largest monitor-line size in bytes */
-        *ecx = CPUID_MWAIT_EMX | CPUID_MWAIT_IBE;
+        *ecx = 0; /* Supported extensions */
         *edx = 0;
         break;
     case 6: