diff --git a/ArmPkg/Library/ArmLib/Common/AArch64/ArmLibSupport.S b/ArmPkg/Library/ArmLib/Common/AArch64/ArmLibSupport.S
index 28db98b417..50faef4ed0 100644
--- a/ArmPkg/Library/ArmLib/Common/AArch64/ArmLibSupport.S
+++ b/ArmPkg/Library/ArmLib/Common/AArch64/ArmLibSupport.S
@@ -184,6 +184,7 @@ ASM_PFX(ArmWriteCptr):
 
 ASM_PFX(ArmWriteScr):
   msr     scr_el3, x0            // Secure configuration register EL3
+  isb
   ret
 
 ASM_PFX(ArmWriteMVBar):
diff --git a/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.S b/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.S
index 59f9918859..085f08bfda 100644
--- a/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.S
+++ b/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.S
@@ -147,6 +147,7 @@ ASM_PFX(ArmReadScr):
 
 ASM_PFX(ArmWriteScr):
   mcr     p15, 0, r0, c1, c1, 0
+  isb
   bx      lr
 
 ASM_PFX(ArmReadHVBar):
diff --git a/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.asm b/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.asm
index bdd862a96a..228d7c8fc1 100644
--- a/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.asm
+++ b/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.asm
@@ -121,6 +121,7 @@
 
  RVCT_ASM_EXPORT ArmWriteScr
   mcr     p15, 0, r0, c1, c1, 0
+  isb
   bx      lr
 
  RVCT_ASM_EXPORT ArmReadHVBar