diff -up sudo-1.7.2p2/toke.c.loop sudo-1.7.2p2/toke.c
--- sudo-1.7.2p2/toke.c.loop	2010-02-09 12:48:33.000000000 +0100
+++ sudo-1.7.2p2/toke.c	2010-02-09 16:54:17.000000000 +0100
@@ -3461,7 +3461,7 @@ init_lexer()
 	    efree(pl);
 	}
 	efree(istack[idepth].path);
-	if (!istack[idepth].keepopen)
+	if (idepth && !istack[idepth].keepopen)
 	    fclose(istack[idepth].bs->yy_input_file);
 	yy_delete_buffer(istack[idepth].bs);
     }
@@ -3486,7 +3486,7 @@ _push_include(path, isdir)
 	}
 	istacksize += SUDOERS_STACK_INCREMENT;
 	istack = (struct include_stack *) realloc(istack,
-	    sizeof(istack) * istacksize);
+	    sizeof(*istack) * istacksize);
 	if (istack == NULL) {
 	    yyerror("unable to allocate memory");
 	    return(FALSE);
diff -up sudo-1.7.2p2/toke.l.loop sudo-1.7.2p2/toke.l
--- sudo-1.7.2p2/toke.l.loop	2010-02-09 12:48:30.000000000 +0100
+++ sudo-1.7.2p2/toke.l	2010-02-09 13:18:27.000000000 +0100
@@ -869,7 +869,7 @@ _push_include(path, isdir)
 	}
 	istacksize += SUDOERS_STACK_INCREMENT;
 	istack = (struct include_stack *) realloc(istack,
-	    sizeof(istack) * istacksize);
+	    sizeof(*istack) * istacksize);
 	if (istack == NULL) {
 	    yyerror("unable to allocate memory");
 	    return(FALSE);