diff --git a/ntoskrnl/ke/amd64/stubs.c b/ntoskrnl/ke/amd64/stubs.c
index cb2d4a37248..7326f7a2cd0 100644
--- a/ntoskrnl/ke/amd64/stubs.c
+++ b/ntoskrnl/ke/amd64/stubs.c
@@ -139,14 +139,18 @@ KiIdleLoop(VOID)
             /* The thread is now running */
             NewThread->State = Running;
 
+#ifdef CONFIG_SMP
             /* Do the swap at SYNCH_LEVEL */
             KfRaiseIrql(SYNCH_LEVEL);
+#endif
 
             /* Switch away from the idle thread */
             KiSwapContext(APC_LEVEL, OldThread);
 
+#ifdef CONFIG_SMP
             /* Go back to DISPATCH_LEVEL */
             KeLowerIrql(DISPATCH_LEVEL);
+#endif
         }
         else
         {
diff --git a/ntoskrnl/ke/arm/thrdini.c b/ntoskrnl/ke/arm/thrdini.c
index 89f1664608b..190b73f926c 100644
--- a/ntoskrnl/ke/arm/thrdini.c
+++ b/ntoskrnl/ke/arm/thrdini.c
@@ -193,8 +193,18 @@ KiIdleLoop(VOID)
             /* The thread is now running */
             NewThread->State = Running;
 
+#ifdef CONFIG_SMP
+            /* Do the swap at SYNCH_LEVEL */
+            KfRaiseIrql(SYNCH_LEVEL);
+#endif
+
             /* Switch away from the idle thread */
             KiSwapContext(APC_LEVEL, OldThread);
+
+#ifdef CONFIG_SMP
+            /* Go back to DISPATCH_LEVEL */
+            KeLowerIrql(DISPATCH_LEVEL);
+#endif
         }
         else
         {
diff --git a/ntoskrnl/ke/i386/thrdini.c b/ntoskrnl/ke/i386/thrdini.c
index cfc497bfc69..3214f560872 100644
--- a/ntoskrnl/ke/i386/thrdini.c
+++ b/ntoskrnl/ke/i386/thrdini.c
@@ -300,8 +300,18 @@ KiIdleLoop(VOID)
             /* The thread is now running */
             NewThread->State = Running;
 
+#ifdef CONFIG_SMP
+            /* Do the swap at SYNCH_LEVEL */
+            KfRaiseIrql(SYNCH_LEVEL);
+#endif
+
             /* Switch away from the idle thread */
             KiSwapContext(APC_LEVEL, OldThread);
+
+#ifdef CONFIG_SMP
+            /* Go back to DISPATCH_LEVEL */
+            KeLowerIrql(DISPATCH_LEVEL);
+#endif
         }
         else
         {