diff --git a/ioapic.c b/ioapic.c
index bf5f793..d343611 100644
--- a/ioapic.c
+++ b/ioapic.c
@@ -62,7 +62,7 @@ ioapicinit(void)
   // Mark all interrupts edge-triggered, active high, disabled,
   // and not routed to any CPUs.
   for(i = 0; i <= maxintr; i++){
-    ioapicwrite(REG_TABLE+2*i, INT_DISABLED | (IRQ_OFFSET + i));
+    ioapicwrite(REG_TABLE+2*i, INT_DISABLED | (T_IRQ0 + i));
     ioapicwrite(REG_TABLE+2*i+1, 0);
   }
 }
@@ -76,6 +76,6 @@ ioapicenable(int irq, int cpunum)
   // Mark interrupt edge-triggered, active high,
   // enabled, and routed to the given cpunum,
   // which happens to be that cpu's APIC ID.
-  ioapicwrite(REG_TABLE+2*irq, IRQ_OFFSET + irq);
+  ioapicwrite(REG_TABLE+2*irq, T_IRQ0 + irq);
   ioapicwrite(REG_TABLE+2*irq+1, cpunum << 24);
 }
diff --git a/lapic.c b/lapic.c
index 19c5b4b..500844a 100644
--- a/lapic.c
+++ b/lapic.c
@@ -52,14 +52,14 @@ lapicinit(int c)
     return;
 
   // Enable local APIC; set spurious interrupt vector.
-  lapicw(SVR, ENABLE | (IRQ_OFFSET+IRQ_SPURIOUS));
+  lapicw(SVR, ENABLE | (T_IRQ0 + IRQ_SPURIOUS));
 
   // The timer repeatedly counts down at bus frequency
   // from lapic[TICR] and then issues an interrupt.  
   // If xv6 cared more about precise timekeeping,
   // TICR would be calibrated using an external time source.
   lapicw(TDCR, X1);
-  lapicw(TIMER, PERIODIC | (IRQ_OFFSET + IRQ_TIMER));
+  lapicw(TIMER, PERIODIC | (T_IRQ0 + IRQ_TIMER));
   lapicw(TICR, 10000000); 
 
   // Disable logical interrupt lines.
@@ -72,7 +72,7 @@ lapicinit(int c)
     lapicw(PCINT, MASKED);
 
   // Map error interrupt to IRQ_ERROR.
-  lapicw(ERROR, IRQ_OFFSET+IRQ_ERROR);
+  lapicw(ERROR, T_IRQ0 + IRQ_ERROR);
 
   // Clear error status register (requires back-to-back writes).
   lapicw(ESR, 0);
diff --git a/picirq.c b/picirq.c
index be505a0..ff86831 100644
--- a/picirq.c
+++ b/picirq.c
@@ -45,7 +45,7 @@ picinit(void)
   outb(IO_PIC1, 0x11);
 
   // ICW2:  Vector offset
-  outb(IO_PIC1+1, IRQ_OFFSET);
+  outb(IO_PIC1+1, T_IRQ0);
 
   // ICW3:  (master PIC) bit mask of IR lines connected to slaves
   //        (slave PIC) 3-bit # of slave's connection to master
@@ -63,7 +63,7 @@ picinit(void)
 
   // Set up slave (8259A-2)
   outb(IO_PIC2, 0x11);                  // ICW1
-  outb(IO_PIC2+1, IRQ_OFFSET + 8);      // ICW2
+  outb(IO_PIC2+1, T_IRQ0 + 8);      // ICW2
   outb(IO_PIC2+1, IRQ_SLAVE);           // ICW3
   // NB Automatic EOI mode doesn't tend to work on the slave.
   // Linux source code says it's "to be investigated".