diff --git a/src/hulk/apic.d b/src/hulk/apic.d
index 59d552e..e35543d 100644
--- a/src/hulk/apic.d
+++ b/src/hulk/apic.d
@@ -7,11 +7,14 @@ import hulk.klog;
 import hulk.hurl;
 import hulk.acpi;
 import hulk.idt;
+import hulk.rtc;
 
 struct apic
 {
     private enum uint PERIODIC_MODE = 0x2_0000u;
 
+    private enum ulong IRQ_RTC = 8u;
+
     static struct ApicRegister
     {
         public uint value;
@@ -52,31 +55,60 @@ struct apic
         ApicRegister divide_configuration;
     }
 
+    static struct IoApicRegisters
+    {
+        ApicRegister address;
+        ApicRegister data;
+    }
+
     private static __gshared ApicRegisters * apic_registers;
+    private static __gshared IoApicRegisters * io_apic_registers;
 
     public static void initialize()
     {
         apic_registers = cast(ApicRegisters *)acpi.apic_address;
+        io_apic_registers = cast(IoApicRegisters *)0xFEC0_0000u;
         hurl.map(cast(ulong)apic_registers, cast(ulong)apic_registers,
                 PT_WRITABLE | PT_WRITE_THROUGH | PT_DISABLE_CACHE | PT_NO_EXECUTE);
+        hurl.map(cast(ulong)io_apic_registers, cast(ulong)io_apic_registers,
+                PT_WRITABLE | PT_WRITE_THROUGH | PT_DISABLE_CACHE | PT_NO_EXECUTE);
         klog.writefln("LAPIC ID: 0x%08x", apic_registers.lapic_id.value);
         klog.writefln("LAPIC version: 0x%08x", apic_registers.lapic_version.value);
         /* Enable local APIC to receive interrupts and set spurious interrupt
          * vector to 0xFF. */
-        apic_registers.spurious_interrupt_vector.value = 0x1FFu;
-        apic_registers.lvt_timer.value = idt.EXCEPTION_LAPIC_TIMER | PERIODIC_MODE;
-        apic_registers.lvt_lint[0].value = idt.EXCEPTION_LAPIC_LINT0;
-        apic_registers.lvt_lint[1].value = idt.EXCEPTION_LAPIC_LINT1;
-        apic_registers.divide_configuration.value = 3u;
+        apic_registers.spurious_interrupt_vector.value = 0x100u | idt.INT_APIC_SPURIOUS;
+        apic_registers.lvt_timer.value = idt.INT_APIC_TIMER;
+        apic_registers.lvt_lint[0].value = idt.INT_APIC_LINT0;
+        apic_registers.lvt_lint[1].value = idt.INT_APIC_LINT1;
+        /* Enable RTC interrupt. */
+        configure_io_apic_irq(IRQ_RTC, idt.INT_APIC_BASE + IRQ_RTC);
     }
 
-    private static void eoi()
+    private static void configure_io_apic_irq(size_t io_apic_irq, size_t interrupt_id)
+    {
+        ulong entry = interrupt_id;
+        io_apic_registers.address.value = cast(uint)(0x10u + io_apic_irq * 2u);
+        io_apic_registers.data.value = entry & 0xFFFF_FFFFu;
+        io_apic_registers.address.value = cast(uint)(0x10u + io_apic_irq * 2u + 1u);
+        io_apic_registers.data.value = entry >> 32u;
+    }
+
+    public static void eoi()
     {
         apic_registers.eoi.value = 0u;
     }
 
     public static void isr(ulong vector)
     {
+        switch (vector)
+        {
+        case idt.INT_APIC_BASE + IRQ_RTC:
+            rtc.isr();
+            break;
+
+        default:
+            break;
+        }
         eoi();
     }
 }
diff --git a/src/hulk/idt.d b/src/hulk/idt.d
index 192f860..9bb1c8c 100644
--- a/src/hulk/idt.d
+++ b/src/hulk/idt.d
@@ -12,9 +12,14 @@ import hulk.apic;
 
 struct idt
 {
-    public static enum ulong EXCEPTION_LAPIC_TIMER = 0x70u;
-    public static enum ulong EXCEPTION_LAPIC_LINT0 = 0x71u;
-    public static enum ulong EXCEPTION_LAPIC_LINT1 = 0x72u;
+    /* The I/O APIC is configured to map IRQ 0 to interrupt 64 (0x40). */
+    public static enum ulong INT_APIC_BASE = 0x40u; /* IRQ 0 */
+    public static enum ulong INT_APIC_COUNT = 24u;
+
+    public static enum ulong INT_APIC_TIMER = 0x70u;
+    public static enum ulong INT_APIC_LINT0 = 0x71u;
+    public static enum ulong INT_APIC_LINT1 = 0x72u;
+    public static enum ulong INT_APIC_SPURIOUS = 0xFFu;
 
     struct idtr_t
     {
@@ -99,19 +104,30 @@ struct idt
 
 public extern(C) void isr(ulong vector, ulong arg)
 {
-    if ((idt.EXCEPTION_LAPIC_TIMER <= vector) && (vector <= idt.EXCEPTION_LAPIC_LINT1))
+    if ((vector >= idt.INT_APIC_BASE) && (vector < (idt.INT_APIC_BASE + idt.INT_APIC_COUNT)))
     {
         apic.isr(vector);
     }
     else
     {
-        console.clear();
-        fb.clear(0xFF8000u);
-        klog.writefln("ISR %u, 0x%x", vector, arg);
-        __asm("cli", "");
-        for (;;)
+        switch (vector)
         {
-            __asm("hlt", "");
+        case idt.INT_APIC_TIMER:
+        case idt.INT_APIC_LINT0:
+        case idt.INT_APIC_LINT1:
+        case idt.INT_APIC_SPURIOUS:
+            apic.isr(vector);
+            break;
+
+        default:
+            console.clear();
+            fb.clear(0xFF8000u);
+            klog.writefln("ISR %u, 0x%x", vector, arg);
+            __asm("cli", "");
+            for (;;)
+            {
+                __asm("hlt", "");
+            }
         }
     }
 }