diff --git a/sdk/xtdk/amd64/hltypes.h b/sdk/xtdk/amd64/hltypes.h
index 68cdfa215..3446d7a0f 100644
--- a/sdk/xtdk/amd64/hltypes.h
+++ b/sdk/xtdk/amd64/hltypes.h
@@ -39,6 +39,9 @@
 #define APIC_VECTOR_PERF                                0xFE
 #define APIC_VECTOR_NMI                                 0xFF
 
+/* APIC SIPI vector shift */
+#define APIC_VECTOR_SIPI_SHIFT                          12
+
 /* APIC destination formats */
 #define APIC_DF_FLAT                                    0xFFFFFFFF
 #define APIC_DF_CLUSTER                                 0x0FFFFFFF
diff --git a/sdk/xtdk/i686/hltypes.h b/sdk/xtdk/i686/hltypes.h
index 898ed95be..1b616933a 100644
--- a/sdk/xtdk/i686/hltypes.h
+++ b/sdk/xtdk/i686/hltypes.h
@@ -45,6 +45,9 @@
 #define APIC_VECTOR_PERF                                0xFE
 #define APIC_VECTOR_NMI                                 0xFF
 
+/* APIC SIPI vector shift */
+#define APIC_VECTOR_SIPI_SHIFT                          12
+
 /* APIC destination formats */
 #define APIC_DF_FLAT                                    0xFFFFFFFF
 #define APIC_DF_CLUSTER                                 0x0FFFFFFF
diff --git a/xtoskrnl/hl/x86/cpu.cc b/xtoskrnl/hl/x86/cpu.cc
index f833a051d..fca616c8a 100644
--- a/xtoskrnl/hl/x86/cpu.cc
+++ b/xtoskrnl/hl/x86/cpu.cc
@@ -163,7 +163,7 @@ HL::Cpu::StartAllProcessors(VOID)
     StartBlock = (PPROCESSOR_START_BLOCK)((PUCHAR)ApVirtualAddress + TrampolineCodeSize);
 
     /* Get SIPI vector */
-    SipiVector = (ULONG)(ApPhysicalAddress.QuadPart >> 12);
+    SipiVector = (ULONG)(ApPhysicalAddress.QuadPart >> APIC_VECTOR_SIPI_SHIFT);
 
     /* Loop over all CPUs */
     CpuNumber = 0;