--- a/sexpr.l	Sat Apr 18 21:50:06 2020 -0400
+++ b/sexpr.l	Sat Jul 18 10:07:34 2020 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2019 Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
+ * Copyright (c) 2015-2020 Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -37,7 +37,7 @@
 
 #define YY_INPUT(buf, result, max_size)	\
 	result = sexpr_reader_input_proc(buf, max_size, yyscanner)
-int sexpr_reader_input_proc(char *buf, int size, yyscan_t scanner);
+static size_t sexpr_reader_input_proc(char *buf, size_t size, yyscan_t scanner);
 
 static void inc_lineno(yyscan_t scanner);
 
@@ -160,10 +160,10 @@
 	out->lineno++;
 }
 
-int sexpr_reader_input_proc(char *buf, int size, yyscan_t scanner)
+static size_t sexpr_reader_input_proc(char *buf, size_t size, yyscan_t scanner)
 {
 	struct sexpr_parser_state *out;
-	int num;
+	ssize_t num;
 
 	out = (struct sexpr_parser_state *) sexpr_reader_get_extra(scanner);
 	num = out->len - out->pos;
@@ -171,8 +171,7 @@
 	if (num <= 0)
 		return 0;
 
-	if (num > size)
-		num = size;
+	num = MIN(num, size);
 
 	memcpy(buf, out->input + out->pos, num);
 	out->pos += num;