diff --git a/ArmPkg/Library/ArmLib/AArch64/ArmLibSupportV8.S b/ArmPkg/Library/ArmLib/AArch64/ArmLibSupportV8.S
index 0e8d21e226..0ae75e4cb9 100644
--- a/ArmPkg/Library/ArmLib/AArch64/ArmLibSupportV8.S
+++ b/ArmPkg/Library/ArmLib/AArch64/ArmLibSupportV8.S
@@ -84,7 +84,7 @@ ASM_FUNC(ArmDisableAllExceptions)
   ret
 
 
-// UINT32
+// UINTN
 // ReadCCSIDR (
 //   IN UINT32 CSSELR
 //   )
diff --git a/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.S b/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.S
index a60a2f6341..af61dbee52 100644
--- a/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.S
+++ b/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.S
@@ -64,7 +64,7 @@ ASM_FUNC(ArmReadIdMmfr4)
   mrc    p15,0,r0,c0,c2,6     @ Read ID_MMFR4 Register
   bx     lr
 
-// UINT32
+// UINTN
 // ReadCCSIDR (
 //   IN UINT32 CSSELR
 //   )
diff --git a/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.asm b/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.asm
index 1679b09b79..81f3cb7999 100644
--- a/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.asm
+++ b/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.asm
@@ -68,7 +68,7 @@
   mrc    p15,0,r0,c0,c2,6     ; Read ID_MMFR4 Register
   bx     LR
 
-// UINT32
+// UINTN
 // ReadCCSIDR (
 //   IN UINT32 CSSELR
 //   )
diff --git a/ArmPkg/Library/ArmLib/ArmLibPrivate.h b/ArmPkg/Library/ArmLib/ArmLibPrivate.h
index 2e90739eb8..8959bdd9d7 100644
--- a/ArmPkg/Library/ArmLib/ArmLibPrivate.h
+++ b/ArmPkg/Library/ArmLib/ArmLibPrivate.h
@@ -61,7 +61,14 @@ CPSRRead (
   VOID
   );
 
-UINT32
+/** Reads the CCSIDR register for the specified cache.
+
+  @param CSSELR The CSSELR cache selection register value.
+
+  @return The contents of the CCSIDR_EL1 register for the specified cache, when in AARCH64 mode.
+          Returns the contents of the CCSIDR register in AARCH32 mode.
+**/
+UINTN
 ReadCCSIDR (
   IN UINT32 CSSELR
   );