diff --git a/src/x87_ops_misc.h b/src/x87_ops_misc.h
index b2f7d32..bde89c7 100644
--- a/src/x87_ops_misc.h
+++ b/src/x87_ops_misc.h
@@ -781,6 +781,8 @@ static int FSTENV()
 {
         FP_ENTER();
         if (fplog) pclog("FSTENV %08X:%08X\n", easeg, cpu_state.eaaddr);
+        cpu_state.npxs = (cpu_state.npxs & ~(7 << 11)) | ((cpu_state.TOP & 7) << 11);
+
         switch ((cr0 & 1) | (cpu_state.op32 & 0x100))
         {
                 case 0x000: /*16-bit real mode*/