diff -up ncurses-5.6/form/frm_driver.c.fieldbuf ncurses-5.6/form/frm_driver.c
--- ncurses-5.6/form/frm_driver.c.fieldbuf	2007-10-09 12:35:24.000000000 +0200
+++ ncurses-5.6/form/frm_driver.c	2007-10-09 13:24:37.000000000 +0200
@@ -4476,7 +4476,7 @@ field_buffer(const FIELD *field, int buf
 	{
 	  wclear(field->working);
 	  mvwadd_wchnstr(field->working, 0, 0, data, size);
-	  mvwinnstr(field->working, 0, 0, result, (int)need + 1);
+	  mvwinnstr(field->working, 0, 0, result, (int)need);
 	}
 #else
       result = Address_Of_Nth_Buffer(field, buffer);