diff --git a/MdePkg/Include/AArch64/AArch64.h b/MdePkg/Include/AArch64/AArch64.h
index 9650608e7b..4e5830c375 100644
--- a/MdePkg/Include/AArch64/AArch64.h
+++ b/MdePkg/Include/AArch64/AArch64.h
@@ -130,6 +130,10 @@
 // build for ARMv8.0, we need to define the register here.
 #define ID_AA64MMFR2_EL1  S3_0_C0_C7_2
 
+// The RNDR register is not recognized by older assemblers,
+// so we need to define it here
+#define RNDR  S3_3_C2_C4_0
+
 #define VECTOR_BASE(tbl)          \
   .section .text.##tbl##,"ax";    \
   .align 11;                      \
diff --git a/MdePkg/Library/BaseRngLib/AArch64/ArmRng.S b/MdePkg/Library/BaseRngLib/AArch64/ArmRng.S
index 27a847b996..98087b51ff 100644
--- a/MdePkg/Library/BaseRngLib/AArch64/ArmRng.S
+++ b/MdePkg/Library/BaseRngLib/AArch64/ArmRng.S
@@ -8,7 +8,7 @@
 #
 #------------------------------------------------------------------------------
 
-#include "BaseRngLibInternals.h"
+#include "ArmRng.h"
 
 .text
 .p2align 2
diff --git a/MdePkg/Library/BaseRngLib/AArch64/ArmRng.asm b/MdePkg/Library/BaseRngLib/AArch64/ArmRng.asm
index 33144196cb..255b9054a1 100644
--- a/MdePkg/Library/BaseRngLib/AArch64/ArmRng.asm
+++ b/MdePkg/Library/BaseRngLib/AArch64/ArmRng.asm
@@ -8,7 +8,7 @@
 ;
 ;------------------------------------------------------------------------------
 
-#include "BaseRngLibInternals.h"
+#include "ArmRng.h"
 
   EXPORT ArmRndr
   AREA BaseLib_LowLevel, CODE, READONLY
diff --git a/MdePkg/Library/BaseRngLib/AArch64/ArmRng.h b/MdePkg/Library/BaseRngLib/AArch64/ArmRng.h
index b4b3c97071..eae1fa9b7e 100644
--- a/MdePkg/Library/BaseRngLib/AArch64/ArmRng.h
+++ b/MdePkg/Library/BaseRngLib/AArch64/ArmRng.h
@@ -11,6 +11,8 @@
 #ifndef ARM_RNG_H_
 #define ARM_RNG_H_
 
+#include <AArch64/AArch64.h>
+
 /**
   Generates a random number using RNDR.
   Returns TRUE on success; FALSE on failure.
diff --git a/MdePkg/Library/BaseRngLib/BaseRngLibInternals.h b/MdePkg/Library/BaseRngLib/BaseRngLibInternals.h
index d0abcc3452..c913f18858 100644
--- a/MdePkg/Library/BaseRngLib/BaseRngLibInternals.h
+++ b/MdePkg/Library/BaseRngLib/BaseRngLibInternals.h
@@ -69,11 +69,4 @@ ArchIsRngSupported (
   VOID
   );
 
-#if defined (MDE_CPU_AARCH64)
-
-// RNDR, Random Number
-#define RNDR  S3_3_C2_C4_0
-
-#endif
-
 #endif // BASE_RNGLIB_INTERNALS_H_