diff --git a/reactos/hal/halx86/generic/usage.c b/reactos/hal/halx86/generic/usage.c
index 1c5a5bb7ff1..e2d967d8498 100644
--- a/reactos/hal/halx86/generic/usage.c
+++ b/reactos/hal/halx86/generic/usage.c
@@ -18,8 +18,8 @@ BOOLEAN HalpGetInfoFromACPI;
 BOOLEAN HalpNMIDumpFlag;
 PUCHAR KdComPortInUse;
 PADDRESS_USAGE HalpAddressUsageList;
-IDTUsageFlags HalpIDTUsageFlags[MAXIMUM_IDTVECTOR];
-IDTUsage HalpIDTUsage[MAXIMUM_IDTVECTOR];
+IDTUsageFlags HalpIDTUsageFlags[MAXIMUM_IDTVECTOR+1];
+IDTUsage HalpIDTUsage[MAXIMUM_IDTVECTOR+1];
 
 USHORT HalpComPortIrqMapping[5][2] =
 {
diff --git a/reactos/hal/halx86/include/halp.h b/reactos/hal/halx86/include/halp.h
index 6db35ab056d..9ca3e9e086b 100644
--- a/reactos/hal/halx86/include/halp.h
+++ b/reactos/hal/halx86/include/halp.h
@@ -865,5 +865,5 @@ extern PWCHAR HalName;
 
 extern KAFFINITY HalpDefaultInterruptAffinity;
 
-extern IDTUsageFlags HalpIDTUsageFlags[MAXIMUM_IDTVECTOR];
+extern IDTUsageFlags HalpIDTUsageFlags[MAXIMUM_IDTVECTOR+1];
 
diff --git a/reactos/ntoskrnl/include/internal/i386/ke.h b/reactos/ntoskrnl/include/internal/i386/ke.h
index f4fe39b97d7..d55fdc17b4e 100644
--- a/reactos/ntoskrnl/include/internal/i386/ke.h
+++ b/reactos/ntoskrnl/include/internal/i386/ke.h
@@ -464,7 +464,7 @@ extern PVOID Ki386IopmSaveArea;
 extern ULONG KeI386EFlagsAndMaskV86;
 extern ULONG KeI386EFlagsOrMaskV86;
 extern BOOLEAN KeI386VirtualIntExtensions;
-extern KIDTENTRY KiIdt[MAXIMUM_IDTVECTOR];
+extern KIDTENTRY KiIdt[MAXIMUM_IDTVECTOR+1];
 extern KDESCRIPTOR KiIdtDescriptor;
 extern BOOLEAN KiI386PentiumLockErrataPresent;
 extern ULONG KeI386NpxPresent;