diff --git a/dlls/rpcrt4/ndr_marshall.c b/dlls/rpcrt4/ndr_marshall.c
index bda04be31f4..80e5b81f515 100644
--- a/dlls/rpcrt4/ndr_marshall.c
+++ b/dlls/rpcrt4/ndr_marshall.c
@@ -361,10 +361,10 @@ typedef struct _NDR_MEMORY_LIST
  *  If the function is unable to allocate memory an ERROR_OUTOFMEMORY
  *  exception is raised.
  */
-void * WINAPI NdrAllocate(MIDL_STUB_MESSAGE *pStubMsg, size_t len)
+void * WINAPI NdrAllocate(MIDL_STUB_MESSAGE *pStubMsg, SIZE_T len)
 {
-    size_t aligned_len;
-    size_t adjusted_len;
+    SIZE_T aligned_len;
+    SIZE_T adjusted_len;
     void *p;
     NDR_MEMORY_LIST *mem_list;
 
@@ -373,7 +373,7 @@ void * WINAPI NdrAllocate(MIDL_STUB_MESSAGE *pStubMsg, size_t len)
     /* check for overflow */
     if (adjusted_len < len)
     {
-        ERR("overflow of adjusted_len %d, len %d\n", adjusted_len, len);
+        ERR("overflow of adjusted_len %ld, len %ld\n", adjusted_len, len);
         RpcRaiseException(RPC_X_BAD_STUB_DATA);
     }
 
diff --git a/include/rpcndr.h b/include/rpcndr.h
index 7c0efafec20..2503a3adbed 100644
--- a/include/rpcndr.h
+++ b/include/rpcndr.h
@@ -652,7 +652,7 @@ RPCRTAPI LONG RPC_ENTRY
   NdrDcomAsyncStubCall( struct IRpcStubBuffer* pThis, struct IRpcChannelBuffer* pChannel, PRPC_MESSAGE pRpcMsg, DWORD * pdwStubPhase );
 
 RPCRTAPI void* RPC_ENTRY
-  NdrAllocate( PMIDL_STUB_MESSAGE pStubMsg, size_t Len ) __WINE_ALLOC_SIZE(2);
+  NdrAllocate( PMIDL_STUB_MESSAGE pStubMsg, SIZE_T Len ) __WINE_ALLOC_SIZE(2);
 
 RPCRTAPI void RPC_ENTRY
   NdrClearOutParameters( PMIDL_STUB_MESSAGE pStubMsg, PFORMAT_STRING pFormat, void *ArgAddr );