diff --git a/reactos/ntoskrnl/ke/i386/ctxswitch.S b/reactos/ntoskrnl/ke/i386/ctxswitch.S
index 45abea5e421..7d3447ebfeb 100644
--- a/reactos/ntoskrnl/ke/i386/ctxswitch.S
+++ b/reactos/ntoskrnl/ke/i386/ctxswitch.S
@@ -13,6 +13,7 @@
 #include <ndk/asm.h>
 .intel_syntax noprefix
 
+#define Ready 1
 #define Running 2
 #define WrDispatchInt 0x1F
 
@@ -346,7 +347,7 @@ BadThread:
 #ifdef CONFIG_SMP
 GetSwapLock:
     /* Acquire the swap lock */
-    cmp [esi+KTHREAD_SWAP_BUSY], 0
+    cmp byte ptr [esi+KTHREAD_SWAP_BUSY], 0
     jz NotBusy
     pause
     jmp GetSwapLock
@@ -559,6 +560,16 @@ NewCr0:
     mov cr0, ecx
     jmp StackOk
 
+#ifdef CONFIG_SMP
+NpxLoaded:
+
+    /* FIXME: TODO */
+    int 3
+
+    /* Jump back */
+    jmp SetStack
+#endif
+
 WmiTrace:
 
     /* No WMI support yet */
@@ -696,8 +707,7 @@ CheckSchedule:
 
 #ifdef CONFIG_SMP
     /* There is, raise IRQL to synch level */
-    mov ecx, SYNCH_LEVEL
-    call @KfRaiseIrql@4
+    call _KeRaiseIrqlToSynchLevel@0
 #endif
     sti
 
@@ -707,7 +717,7 @@ CheckSchedule:
     mov byte ptr [edi+KTHREAD_SWAP_BUSY], 1
 
     /* Acquire the PRCB Lock */
-    lock bts [ebx+KPCR_PRCB_PRCB_LOCK], 0
+    lock bts dword ptr [ebx+KPCR_PRCB_PRCB_LOCK], 0
     jnb CheckNext
     lea ecx, [ebx+KPCR_PRCB_PRCB_LOCK]
     call @KefAcquireSpinLockAtDpcLevel@4
@@ -731,7 +741,7 @@ CheckNext:
 #ifdef CONFIG_SMP
     /* Disable the idle scheduler and release the PRCB lock */
     and byte ptr [ebx+KPCR_PRCB_IDLE_SCHEDULE], 0
-    and [ebx+KPCR_PRCB_PRCB_LOCK], 0
+    and dword ptr [ebx+KPCR_PRCB_PRCB_LOCK], 0
 #endif
 
 SwapContext:
@@ -764,7 +774,7 @@ NoNextThread:
     jz CpuIdle
 
     /* It is, so call the scheduler */
-    lea ecx, [ebx+KPCR_PRCBDATA]
+    lea ecx, [ebx+KPCR_PRCB_DATA]
     call @KiIdleSchedule@4
     test eax, eax
 
diff --git a/reactos/ntoskrnl/ke/i386/trap.s b/reactos/ntoskrnl/ke/i386/trap.s
index 2f3aec94e87..d438650c2f3 100644
--- a/reactos/ntoskrnl/ke/i386/trap.s
+++ b/reactos/ntoskrnl/ke/i386/trap.s
@@ -2455,9 +2455,20 @@ CheckQuantum:
     mov edi, [ebx+KPCR_CURRENT_THREAD]
 
 #ifdef CONFIG_SMP
-    #error SMP Interrupt not handled!
+    /* Raise to synch level */
+    call _KeRaiseIrqlToSynchLevel@0
+
+    /* Set context swap busy */
+    mov byte ptr [edi+KTHREAD_SWAP_BUSY], 1
+
+    /* Acquire the PRCB Lock */
+    lock bts dword ptr [ebx+KPCR_PRCB_PRCB_LOCK], 0
+    jnb GetNext
+    lea ecx, [ebx+KPCR_PRCB_PRCB_LOCK]
+    call @KefAcquireSpinLockAtDpcLevel@4
 #endif
 
+GetNext:
     /* Get the next thread and clear it */
     mov esi, [ebx+KPCR_PRCB_NEXT_THREAD]
     and dword ptr [ebx+KPCR_PRCB_NEXT_THREAD], 0
@@ -2476,6 +2487,12 @@ CheckQuantum:
     mov cl, APC_LEVEL
     call @KiSwapContextInternal@0
 
+#ifdef CONFIG_SMP
+    /* Lower IRQL back to dispatch */
+    mov cl, DISPATCH_LEVEL
+    call @KfLowerIrql@4
+#endif
+
     /* Restore registers */
     mov ebp, [esp+0]
     mov edi, [esp+4]
@@ -2617,7 +2634,7 @@ SpuriousInt:
 
 #ifdef CONFIG_SMP
 IntSpin:
-    SPIN_ON_LOCK esi, GetIntLock
+    SPIN_ON_LOCK(esi, GetIntLock)
 #endif
 
 IsrTimeout: