diff --git a/ArmPkg/Drivers/CpuDxe/AArch64/Mmu.c b/ArmPkg/Drivers/CpuDxe/AArch64/Mmu.c
index 8997b7f61f..8bb33046e7 100644
--- a/ArmPkg/Drivers/CpuDxe/AArch64/Mmu.c
+++ b/ArmPkg/Drivers/CpuDxe/AArch64/Mmu.c
@@ -305,7 +305,7 @@ EfiAttributeToArmAttribute (
 
   // Determine protection attributes
   if ((EfiAttributes & EFI_MEMORY_RO) != 0) {
-    ArmAttributes |= TT_AP_RO_RO;
+    ArmAttributes |= TT_AP_NO_RO;
   }
 
   // Process eXecute Never attribute
diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
index 89da40fd8e..4a0513392a 100644
--- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
+++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
@@ -393,7 +393,7 @@ GcdAttributeToPageAttribute (
   }
 
   if ((GcdAttributes & EFI_MEMORY_RO) != 0) {
-    PageAttributes |= TT_AP_RO_RO;
+    PageAttributes |= TT_AP_NO_RO;
   }
 
   return PageAttributes | TT_AF;
@@ -492,7 +492,7 @@ ArmSetMemoryRegionReadOnly (
   return SetMemoryRegionAttribute (
            BaseAddress,
            Length,
-           TT_AP_RO_RO,
+           TT_AP_NO_RO,
            ~TT_ADDRESS_MASK_BLOCK_ENTRY
            );
 }
@@ -506,7 +506,7 @@ ArmClearMemoryRegionReadOnly (
   return SetMemoryRegionAttribute (
            BaseAddress,
            Length,
-           TT_AP_RW_RW,
+           TT_AP_NO_RW,
            ~(TT_ADDRESS_MASK_BLOCK_ENTRY | TT_AP_MASK)
            );
 }