diff --git a/paw/stos/head/arch/amd64/gdt.h b/paw/stos/head/arch/amd64/gdt.h
new file mode 100644
index 0000000..107c70f
--- /dev/null
+++ b/paw/stos/head/arch/amd64/gdt.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Global descriptor table
+ * Author:      Chloe M.
+ */
+
+#ifndef _MACHINE_GDT_H_
+#define _MACHINE_GDT_H_ 1
+
+/* Number of GDT entries */
+#define GDT_ENTRY_COUNT 7
+
+/* Kernel code/data */
+#define GDT_KCODE  0x08
+#define GDT_KDATA  0x10
+
+/* User code/data */
+#define GDT_UCODE  0x18
+#define GDT_UDATA  0x20
+
+/* Task state segment */
+#define GDT_TSS    0x28
+#define GDT_TSS_INDEX 0x05
+
+#endif  /* !_MACHINE_GDT_H_ */