diff --git a/SecurityPkg/Include/Library/RpmcLib.h b/SecurityPkg/Include/Library/RpmcLib.h
index 5882bfae2f..3c15bce1ce 100644
--- a/SecurityPkg/Include/Library/RpmcLib.h
+++ b/SecurityPkg/Include/Library/RpmcLib.h
@@ -14,6 +14,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 /**
   Requests the monotonic counter from the designated RPMC counter.
 
+  @param[in]    CounterIndex            The RPMC index
   @param[out]   CounterValue            A pointer to a buffer to store the RPMC value.
 
   @retval       EFI_SUCCESS             The operation completed successfully.
@@ -23,12 +24,15 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 EFI_STATUS
 EFIAPI
 RequestMonotonicCounter (
+  IN  UINT8   CounterIndex,
   OUT UINT32  *CounterValue
   );
 
 /**
   Increments the monotonic counter in the SPI flash device by 1.
 
+  @param[in]    CounterIndex            The RPMC index
+
   @retval       EFI_SUCCESS             The operation completed successfully.
   @retval       EFI_DEVICE_ERROR        A device error occurred while attempting to update the counter.
   @retval       EFI_UNSUPPORTED         The operation is un-supported.
@@ -36,7 +40,7 @@ RequestMonotonicCounter (
 EFI_STATUS
 EFIAPI
 IncrementMonotonicCounter (
-  VOID
+  IN  UINT8   CounterIndex
   );
 
 #endif
diff --git a/SecurityPkg/Library/RpmcLibNull/RpmcLibNull.c b/SecurityPkg/Library/RpmcLibNull/RpmcLibNull.c
index e1dd09eb10..697e493a7c 100644
--- a/SecurityPkg/Library/RpmcLibNull/RpmcLibNull.c
+++ b/SecurityPkg/Library/RpmcLibNull/RpmcLibNull.c
@@ -12,6 +12,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 /**
   Requests the monotonic counter from the designated RPMC counter.
 
+  @param[in]    CounterIndex            The RPMC index
   @param[out]   CounterValue            A pointer to a buffer to store the RPMC value.
 
   @retval       EFI_SUCCESS             The operation completed successfully.
@@ -21,6 +22,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 EFI_STATUS
 EFIAPI
 RequestMonotonicCounter (
+  IN  UINT8   CounterIndex,
   OUT UINT32  *CounterValue
   )
 {
@@ -31,6 +33,8 @@ RequestMonotonicCounter (
 /**
   Increments the monotonic counter in the SPI flash device by 1.
 
+  @param[in]    CounterIndex            The RPMC index
+
   @retval       EFI_SUCCESS             The operation completed successfully.
   @retval       EFI_DEVICE_ERROR        A device error occurred while attempting to update the counter.
   @retval       EFI_UNSUPPORTED         The operation is un-supported.
@@ -38,7 +42,7 @@ RequestMonotonicCounter (
 EFI_STATUS
 EFIAPI
 IncrementMonotonicCounter (
-  VOID
+  IN  UINT8   CounterIndex
   )
 {
   ASSERT (FALSE);