diff --git a/IntelFsp2Pkg/Include/Library/FspSecPlatformLib.h b/IntelFsp2Pkg/Include/Library/FspSecPlatformLib.h
index 598fdb9ec5..675b3ab02f 100644
--- a/IntelFsp2Pkg/Include/Library/FspSecPlatformLib.h
+++ b/IntelFsp2Pkg/Include/Library/FspSecPlatformLib.h
@@ -112,7 +112,7 @@ FspMultiPhaseSiInitApiHandler (
 BOOLEAN
 EFIAPI
 FspMultiPhasePlatformGetNumberOfPhases (
-  IN     UINTN   ApiIdx,
+  IN     UINT32  ApiIdx,
   IN OUT UINT32  *NumberOfPhasesSupported
   );
 
diff --git a/IntelFsp2Pkg/Library/SecFspSecPlatformLibNull/PlatformSecLibNull.c b/IntelFsp2Pkg/Library/SecFspSecPlatformLibNull/PlatformSecLibNull.c
index 9c1b5b32e9..67b8247510 100644
--- a/IntelFsp2Pkg/Library/SecFspSecPlatformLibNull/PlatformSecLibNull.c
+++ b/IntelFsp2Pkg/Library/SecFspSecPlatformLibNull/PlatformSecLibNull.c
@@ -62,7 +62,7 @@ FspMultiPhaseSiInitApiHandler (
 BOOLEAN
 EFIAPI
 FspMultiPhasePlatformGetNumberOfPhases (
-  IN     UINT8   ApiIdx,
+  IN     UINT32  ApiIdx,
   IN OUT UINT32  *NumberOfPhasesSupported
   )
 {