diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S b/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S
index e4a10c2526..a188b40ed4 100644
--- a/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S
+++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S
@@ -402,10 +402,12 @@ ASM_FUNC(ArmReadIdAA64Pfr1)
 
 ASM_FUNC(ArmSetPan)
   msr   pan, #1
+  isb
   ret
 
 ASM_FUNC(ArmClearPan)
   msr   pan, #0
+  isb
   ret
 
 ASM_FUNCTION_REMOVE_IF_UNREFERENCED
diff --git a/ArmPkg/Library/ArmLib/Arm/ArmLibSupport.S b/ArmPkg/Library/ArmLib/Arm/ArmLibSupport.S
index bd2861c444..6bde5bacc3 100644
--- a/ArmPkg/Library/ArmLib/Arm/ArmLibSupport.S
+++ b/ArmPkg/Library/ArmLib/Arm/ArmLibSupport.S
@@ -154,10 +154,12 @@ ASM_FUNC (ArmGetPhysicalAddressBits)
 
 ASM_FUNC(ArmSetPan)
   setpan #1
+  isb
   bx     LR
 
 ASM_FUNC(ArmClearPan)
   setpan #0
+  isb
   bx     LR
 
 ASM_FUNCTION_REMOVE_IF_UNREFERENCED