diff --git a/awkgram.y b/awkgram.y
index 24acc460..fc7a9ba3 100644
--- a/awkgram.y
+++ b/awkgram.y
@@ -3105,11 +3105,6 @@ get_src_buf()
 	int savelen;
 	struct stat sbuf;
 
-	/*
-	 * No argument prototype on readfunc on purpose,
-	 * avoids problems with some ancient systems where
-	 * the types of arguments to read() aren't up to date.
-	 */
 	static ssize_t (*readfunc)(int, void *, size_t) = NULL;
 
 	if (readfunc == NULL) {
diff --git a/io.c b/io.c
index acb707b0..f0c7901c 100644
--- a/io.c
+++ b/io.c
@@ -3388,7 +3388,7 @@ iop_alloc(int fd, const char *name, int errno_val)
 
 	iop->public.fd = fd;
 	iop->public.name = name;
-	iop->public.read_func = ( ssize_t(*)() ) read;
+	iop->public.read_func = ( ssize_t(*)(int, void *, size_t) ) read;
 	iop->valid = false;
 	iop->errcode = errno_val;
 
@@ -4448,7 +4448,7 @@ get_read_timeout(IOBUF *iop)
 	}
 
 	/* overwrite read routine only if an extension has not done so */
-	if ((iop->public.read_func == ( ssize_t(*)() ) read) && tmout > 0)
+	if ((iop->public.read_func == ( ssize_t(*)(int, void *, size_t) ) read) && tmout > 0)
 		iop->public.read_func = read_with_timeout;
 
 	return tmout;