diff --git a/headers/private/kernel/arch/int.h b/headers/private/kernel/arch/int.h
index 6d4afc6f67..0bfd94febb 100644
--- a/headers/private/kernel/arch/int.h
+++ b/headers/private/kernel/arch/int.h
@@ -34,7 +34,7 @@ void arch_int_enable_io_interrupt(int irq);
 void arch_int_disable_io_interrupt(int irq);
 void arch_int_configure_io_interrupt(int irq, uint32 config);
 bool arch_int_are_interrupts_enabled(void);
-void arch_int_assign_to_cpu(int32 irq, int32 cpu);
+int32 arch_int_assign_to_cpu(int32 irq, int32 cpu);
 
 #ifdef __cplusplus
 }
diff --git a/src/system/kernel/arch/arm/arch_int.cpp b/src/system/kernel/arch/arm/arch_int.cpp
index 3bb5c2c80a..67aabe845e 100644
--- a/src/system/kernel/arch/arm/arch_int.cpp
+++ b/src/system/kernel/arch/arm/arch_int.cpp
@@ -84,12 +84,14 @@ arch_int_disable_io_interrupt(int irq)
 
 /* arch_int_*_interrupts() and friends are in arch_asm.S */
 
-void
+int32
 arch_int_assign_to_cpu(int32 irq, int32 cpu)
 {
-	// intentionally left blank; no SMP support (yet)
+	// Not yet supported.
+	return 0;
 }
 
+
 static void
 print_iframe(const char *event, struct iframe *frame)
 {
diff --git a/src/system/kernel/arch/arm64/arch_int.cpp b/src/system/kernel/arch/arm64/arch_int.cpp
index 23d5c7f8bf..34c452adeb 100644
--- a/src/system/kernel/arch/arm64/arch_int.cpp
+++ b/src/system/kernel/arch/arm64/arch_int.cpp
@@ -39,10 +39,11 @@ arch_int_disable_io_interrupt(int irq)
 }
 
 
-void
+int32
 arch_int_assign_to_cpu(int32 irq, int32 cpu)
 {
-	// intentionally left blank; no SMP support (yet)
+	// Not yet supported.
+	return 0;
 }
 
 
diff --git a/src/system/kernel/arch/m68k/arch_int.cpp b/src/system/kernel/arch/m68k/arch_int.cpp
index 6583b75253..e7c995b4e3 100644
--- a/src/system/kernel/arch/m68k/arch_int.cpp
+++ b/src/system/kernel/arch/m68k/arch_int.cpp
@@ -95,10 +95,11 @@ arch_int_disable_io_interrupt(int irq)
 /* arch_int_*_interrupts() and friends are in arch_asm.S */
 
 
-void
+int32
 arch_int_assign_to_cpu(int32 irq, int32 cpu)
 {
-	// intentionally left blank; no SMP support (yet)
+	// Not yet supported.
+	return 0;
 }
 
 
diff --git a/src/system/kernel/arch/ppc/arch_int.cpp b/src/system/kernel/arch/ppc/arch_int.cpp
index 5e5ce87a9f..9c358d443d 100644
--- a/src/system/kernel/arch/ppc/arch_int.cpp
+++ b/src/system/kernel/arch/ppc/arch_int.cpp
@@ -571,7 +571,9 @@ ppc_set_current_cpu_exception_context(struct ppc_cpu_exception_context *context)
 }
 
 
-void
+int32
 arch_int_assign_to_cpu(int32 irq, int32 cpu)
 {
+	// Not yet supported.
+	return 0;
 }
diff --git a/src/system/kernel/arch/riscv64/arch_int.cpp b/src/system/kernel/arch/riscv64/arch_int.cpp
index cbcf90137e..de42b07532 100644
--- a/src/system/kernel/arch/riscv64/arch_int.cpp
+++ b/src/system/kernel/arch/riscv64/arch_int.cpp
@@ -549,8 +549,9 @@ arch_int_disable_io_interrupt(int irq)
 }
 
 
-void
+int32
 arch_int_assign_to_cpu(int32 irq, int32 cpu)
 {
-	// SMP not yet supported
+	// Not yet supported.
+	return 0;
 }
diff --git a/src/system/kernel/arch/sparc/arch_int.cpp b/src/system/kernel/arch/sparc/arch_int.cpp
index 885044d2aa..5abdffdd82 100644
--- a/src/system/kernel/arch/sparc/arch_int.cpp
+++ b/src/system/kernel/arch/sparc/arch_int.cpp
@@ -50,7 +50,9 @@ arch_int_disable_io_interrupt(int irq)
 }
 
 
-void
+int32
 arch_int_assign_to_cpu(int32 irq, int32 cpu)
 {
+	// Not yet supported.
+	return 0;
 }
diff --git a/src/system/kernel/arch/x86/arch_int.cpp b/src/system/kernel/arch/x86/arch_int.cpp
index 416e9d21c4..025d431dd6 100644
--- a/src/system/kernel/arch/x86/arch_int.cpp
+++ b/src/system/kernel/arch/x86/arch_int.cpp
@@ -424,7 +424,7 @@ arch_int_are_interrupts_enabled(void)
 }
 
 
-void
+int32
 arch_int_assign_to_cpu(int32 irq, int32 cpu)
 {
 	switch (sVectorSources[irq]) {
@@ -440,6 +440,7 @@ arch_int_assign_to_cpu(int32 irq, int32 cpu)
 		default:
 			break;
 	}
+	return cpu;
 }
 
 
diff --git a/src/system/kernel/int.cpp b/src/system/kernel/int.cpp
index 1cd125538b..13c1569967 100644
--- a/src/system/kernel/int.cpp
+++ b/src/system/kernel/int.cpp
@@ -468,7 +468,7 @@ install_io_interrupt_handler(long vector, interrupt_handler handler, void *data,
 		&& sVectors[vector].assigned_cpu->cpu == -1) {
 
 		int32 cpuID = assign_cpu();
-		arch_int_assign_to_cpu(vector, cpuID);
+		cpuID = arch_int_assign_to_cpu(vector, cpuID);
 		sVectors[vector].assigned_cpu->cpu = cpuID;
 
 		cpu_ent* cpu = &gCPU[cpuID];
@@ -743,10 +743,9 @@ void assign_io_interrupt_to_cpu(long vector, int32 newCPU)
 	list_remove_item(&cpu->irqs, sVectors[vector].assigned_cpu);
 	locker.Unlock();
 
+	newCPU = arch_int_assign_to_cpu(vector, newCPU);
+	sVectors[vector].assigned_cpu->cpu = newCPU;
 	cpu = &gCPU[newCPU];
 	locker.SetTo(cpu->irqs_lock, false);
-	sVectors[vector].assigned_cpu->cpu = newCPU;
-	arch_int_assign_to_cpu(vector, newCPU);
 	list_add_item(&cpu->irqs, sVectors[vector].assigned_cpu);
 }
-