diff --git a/3rdparty/fcpp/cpp2.c b/3rdparty/fcpp/cpp2.c
index 1d4fa154..c2f75dd9 100644
--- a/3rdparty/fcpp/cpp2.c
+++ b/3rdparty/fcpp/cpp2.c
@@ -627,7 +627,7 @@ ReturnCode openinclude( struct Global *global,
 
     char **incptr;
     char tmpname[NWORK]; /* Filename work area    */
-    int len;
+    size_t len;
 
     #if HOST == SYS_AMIGADOS
     if( strchr (filename, ':') != NULL )