diff --git a/sc2/src/sc2code/commglue.c b/sc2/src/sc2code/commglue.c
index d90890efa..9b7d9a838 100644
--- a/sc2/src/sc2code/commglue.c
+++ b/sc2/src/sc2code/commglue.c
@@ -21,6 +21,8 @@
 #include "races.h"
 
 #include <stdarg.h>
+#include <stdlib.h>
+#include <stddef.h>
 #include <assert.h>
 
 int NPCNumberPhrase (int number, UNICODE **ptrack);
@@ -281,7 +283,7 @@ construct_response (UNICODE *buf, int R /* promoted from RESPONSE_REF */, ...)
 	// XXX: this should someday be changed so that the function takes
 	//   the buffer size as an argument
 	if ((buf_start == shared_phrase_buf) &&
-			(buf - shared_phrase_buf > sizeof (shared_phrase_buf)))
+			(buf - shared_phrase_buf > (ptrdiff_t) sizeof (shared_phrase_buf)))
 	{
 		fprintf (stderr, "Error: shared_phrase_buf size exceeded,"
 				" please increase!\n");
diff --git a/sc2/src/sc2code/libs/strings/unicode.c b/sc2/src/sc2code/libs/strings/unicode.c
index 1f41bd6ff..fbbe49d7b 100644
--- a/sc2/src/sc2code/libs/strings/unicode.c
+++ b/sc2/src/sc2code/libs/strings/unicode.c
@@ -16,6 +16,7 @@
 
 #include "port.h"
 
+#include <ctype.h>
 #include <stddef.h>
 #include <stdio.h>
 #include <string.h>