diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S
index 887439bc042..1f0d8057926 100644
--- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S
+++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S
@@ -65,6 +65,7 @@
   // write updated entry
   str   x1, [x0]
   dsb   nshst
+  isb
 
 .L2_\@:
   .endm