diff --git a/reactos/tools/mkhive/cmi.c b/reactos/tools/mkhive/cmi.c
index cb79a18c3b5..71550c7895f 100644
--- a/reactos/tools/mkhive/cmi.c
+++ b/reactos/tools/mkhive/cmi.c
@@ -31,7 +31,7 @@ CmpAllocate(
 	IN SIZE_T Size,
 	IN BOOLEAN Paged)
 {
-	return (PVOID) malloc(Size);
+	return (PVOID) malloc((size_t)Size);
 }
 
 static VOID
diff --git a/reactos/tools/mkhive/mkhive.h b/reactos/tools/mkhive/mkhive.h
index bb7da55512c..6a1aaff68f6 100644
--- a/reactos/tools/mkhive/mkhive.h
+++ b/reactos/tools/mkhive/mkhive.h
@@ -28,6 +28,7 @@
 #define __MKHIVE_H__
 
 #include <stdio.h>
+#include <stdlib.h>
 
 /* We have to do this because psdk/windef.h will _always_ define _WIN32... */
 #if defined(_WIN32) || defined(_WIN64)
diff --git a/reactos/tools/mkhive/rtl.c b/reactos/tools/mkhive/rtl.c
index ed6711dd075..913a79eaa40 100644
--- a/reactos/tools/mkhive/rtl.c
+++ b/reactos/tools/mkhive/rtl.c
@@ -4,6 +4,8 @@
  * PURPOSE:         Runtime Library
  */
 
+#include <stdlib.h>
+
 #define RTL_H
 
 #define NTOS_MODE_USER
@@ -11,7 +13,7 @@
 #include <ntddk.h>
 #include <bitmap.c>
 
-SIZE_T xwcslen( PWSTR String ) {
+SIZE_T xwcslen( PCWSTR String ) {
 	SIZE_T i;
 
 	for( i = 0; String[i]; i++ );