diff --git a/include/date.cpp b/include/date.cpp
index 53642c9f3..bb1fe30ff 100755
--- a/include/date.cpp
+++ b/include/date.cpp
@@ -1,12 +1,7 @@
-#include <ctype.h>
-#include <stdlib.h>
-#include <time.h>
-
 #define __DATE_CPP
 #include <date.h>
 #include <diction.h>
 #include <real.h>
-#include <strings.h>
 
 #define DAYYEAR  365
 #define DAYBIAS  36525L
@@ -157,7 +152,7 @@ void  TDate::set_day(int n)
 }  
 void  TDate::set_month(int n) 
 { 
-  CHECK(n > 0 && n < 13, "TDate::set_month: mese impossibile");
+  CHECK(n > 0 && n <= 12, "TDate::set_month: mese impossibile");
   _val = makedata(day(), n, year());   
 }