diff --git a/putty.h b/putty.h
index eebd3da3..ad7e3903 100644
--- a/putty.h
+++ b/putty.h
@@ -2,6 +2,7 @@
 #define PUTTY_PUTTY_H
 
 #include <stdio.h>		       /* for FILENAME_MAX */
+#include <stddef.h>		       /* for wchar_t */
 
 /*
  * Global variables. Most modules declare these `extern', but
diff --git a/wcwidth.c b/wcwidth.c
index f76fd862..2d7a0935 100644
--- a/wcwidth.c
+++ b/wcwidth.c
@@ -6,7 +6,7 @@
  * Markus Kuhn -- 2001-01-12 -- public domain
  */
 
-#include <wchar.h>
+#include <stddef.h>
 
 struct interval {
   unsigned short first;