diff --git a/src/hulk/gdt.d b/src/hulk/gdt.d
new file mode 100644
index 0000000..83c41c6
--- /dev/null
+++ b/src/hulk/gdt.d
@@ -0,0 +1,58 @@
+/**
+ * GDT (Global Descriptor Table) functionality.
+ */
+module hulk.gdt;
+
+import ldc.llvmasm;
+
+struct gdt
+{
+    struct gdtr_t
+    {
+        ushort limit;
+        align(2) ulong offset;
+    }
+    static assert(gdtr_t.sizeof == 10u);
+
+    private enum size_t SELECTOR_NULL = 0x00u;
+    private enum size_t SELECTOR_KERNEL_CODE = 0x08u;
+    private enum size_t SELECTOR_KERNEL_DATA = 0x10u;
+    private enum size_t SELECTOR_COUNT = 3u;
+
+    static __gshared ulong[SELECTOR_COUNT] gdt;
+    static __gshared gdtr_t gdtr;
+
+    public static void initialize()
+    {
+        gdt[SELECTOR_KERNEL_CODE / ulong.sizeof] = 0x00_A_F_9A_000000_0000u;
+        gdt[SELECTOR_KERNEL_DATA / ulong.sizeof] = 0x00_C_F_92_000000_0000u;
+        gdtr.limit = gdt.sizeof - 1u;
+        gdtr.offset = cast(ulong)&gdt;
+        lgdt(&gdtr);
+        load_data_selectors(SELECTOR_KERNEL_DATA);
+        load_code_selector(SELECTOR_KERNEL_CODE);
+    }
+
+    private static void lgdt(gdtr_t * gdtr)
+    {
+        __asm("lgdt $0", "*m", gdtr);
+    }
+
+    private static void load_data_selectors(ulong selector)
+    {
+        __asm(`mov %ax, %ds
+               mov %ax, %es
+               mov %ax, %fs
+               mov %ax, %gs
+               mov %ax, %ss`, "{rax}", selector);
+    }
+
+    private static void load_code_selector(ulong selector)
+    {
+        __asm(`push %rax
+               movabs $$1f, %rax
+               push %rax
+               lretq
+               1:`, "{rax}", selector);
+    }
+}
diff --git a/src/hulk/hulk.d b/src/hulk/hulk.d
index 34283a8..f6c695d 100644
--- a/src/hulk/hulk.d
+++ b/src/hulk/hulk.d
@@ -13,6 +13,7 @@ import hulk.klog;
 import hulk.hurl;
 import hulk.hippo;
 import hulk.pci;
+import hulk.gdt;
 
 extern extern(C) __gshared ubyte _hulk_total_size;
 
@@ -31,6 +32,7 @@ private __gshared HulkHeader hulk_header = {
  */
 void hulk_start()
 {
+    gdt.initialize();
     fb.initialize(cast(uint *)HULK_VIRTUAL_FRAMEBUFFER_ADDRESS, hulk_header.bootinfo.fb.width, hulk_header.bootinfo.fb.height, hulk_header.bootinfo.fb.stride);
     console.initialize();
     console.clear();