diff --git a/shellcode_hypervisor/boot_linux.c b/shellcode_hypervisor/boot_linux.c
index 8a2f811..78537aa 100644
--- a/shellcode_hypervisor/boot_linux.c
+++ b/shellcode_hypervisor/boot_linux.c
@@ -159,7 +159,7 @@ void entry(void) {
   }
 
   // Disable IOMMU.
-  *(volatile uint64_t *)0xfdd80018 &= ~1;
+  *(volatile uint64_t *)(AMDIOMMU_MMIO_BASE + AMDIOMMU_CTRL) &= ~1;
 
   memcpy(&info, (void *)(cave_linux_info), sizeof(struct linux_info));
 
diff --git a/shellcode_hypervisor/boot_linux.h b/shellcode_hypervisor/boot_linux.h
index fbe3510..452a36b 100644
--- a/shellcode_hypervisor/boot_linux.h
+++ b/shellcode_hypervisor/boot_linux.h
@@ -37,7 +37,10 @@
 #define DCHUBBUB_WHITELIST_BASE_ADDR_0 0x24878
 #define DCHUBBUB_WHITELIST_TOP_ADDR_0 0x2487c
 
+#define AMDIOMMU_MMIO_BASE 0xfdd80000
+#define AMDIOMMU_CTRL 0x18
+
 #define MAXCPU 16
 
 void entry(void);
-void boot_linux(void);
\ No newline at end of file
+void boot_linux(void);