diff --git a/headers/private/kernel/arch/arm/arch_cpu.h b/headers/private/kernel/arch/arm/arch_cpu.h
index c3e4908833..aa28d75730 100644
--- a/headers/private/kernel/arch/arm/arch_cpu.h
+++ b/headers/private/kernel/arch/arm/arch_cpu.h
@@ -11,6 +11,10 @@
 	// TODO: Could be 32-bits sometimes?
 
 
+#define set_ac()
+#define clear_ac()
+
+
 #ifndef _ASSEMBLER
 
 #include <arch/arm/arch_thread_types.h>
diff --git a/headers/private/kernel/arch/m68k/arch_cpu.h b/headers/private/kernel/arch/m68k/arch_cpu.h
index 9d41e35863..62919f18fa 100644
--- a/headers/private/kernel/arch/m68k/arch_cpu.h
+++ b/headers/private/kernel/arch/m68k/arch_cpu.h
@@ -18,6 +18,10 @@
 #define CACHE_LINE_SIZE		16
 
 
+#define set_ac()
+#define clear_ac()
+
+
 #define SR_IP_MASK 0x0700
 #define SR_S 0x2000
 #define M68K_SR_S 13
diff --git a/headers/private/kernel/arch/ppc/arch_cpu.h b/headers/private/kernel/arch/ppc/arch_cpu.h
index 89dfe58f9a..563f04ddfe 100644
--- a/headers/private/kernel/arch/ppc/arch_cpu.h
+++ b/headers/private/kernel/arch/ppc/arch_cpu.h
@@ -16,6 +16,10 @@
 	// 128 Byte lines on PPC970
 
 
+#define set_ac()
+#define clear_ac()
+
+
 struct iframe {
 	uint32 vector;
 	uint32 srr0;