diff --git a/usr.bin/sort/bwstring.c b/usr.bin/sort/bwstring.c
--- a/usr.bin/sort/bwstring.c
+++ b/usr.bin/sort/bwstring.c
@@ -470,115 +470,6 @@
 	}
 }
 
-/*
- * Allocate and read a binary string from file.
- * The strings are nl-ended or zero-ended, depending on the sort setting.
- */
-struct bwstring *
-bwsfgetln(FILE *f, size_t *len, bool zero_ended, struct reader_buffer *rb)
-{
-	wint_t eols;
-
-	eols = zero_ended ? btowc('\0') : btowc('\n');
-
-	if (!zero_ended && (mb_cur_max > 1)) {
-		wchar_t *ret;
-
-		ret = fgetwln(f, len);
-
-		if (ret == NULL) {
-			if (!feof(f))
-				err(2, NULL);
-			return (NULL);
-		}
-		if (*len > 0) {
-			if (ret[*len - 1] == (wchar_t)eols)
-				--(*len);
-		}
-		return (bwssbdup(ret, *len));
-
-	} else if (!zero_ended && (mb_cur_max == 1)) {
-		char *ret;
-
-		ret = fgetln(f, len);
-
-		if (ret == NULL) {
-			if (!feof(f))
-				err(2, NULL);
-			return (NULL);
-		}
-		if (*len > 0) {
-			if (ret[*len - 1] == '\n')
-				--(*len);
-		}
-		return (bwscsbdup((unsigned char *)ret, *len));
-
-	} else {
-		*len = 0;
-
-		if (feof(f))
-			return (NULL);
-
-		if (2 >= rb->fgetwln_z_buffer_size) {
-			rb->fgetwln_z_buffer_size += 256;
-			rb->fgetwln_z_buffer = sort_realloc(rb->fgetwln_z_buffer,
-			    sizeof(wchar_t) * rb->fgetwln_z_buffer_size);
-		}
-		rb->fgetwln_z_buffer[*len] = 0;
-
-		if (mb_cur_max == 1)
-			while (!feof(f)) {
-				int c;
-
-				c = fgetc(f);
-
-				if (c == EOF) {
-					if (*len == 0)
-						return (NULL);
-					goto line_read_done;
-				}
-				if (c == eols)
-					goto line_read_done;
-
-				if (*len + 1 >= rb->fgetwln_z_buffer_size) {
-					rb->fgetwln_z_buffer_size += 256;
-					rb->fgetwln_z_buffer = sort_realloc(rb->fgetwln_z_buffer,
-					    SIZEOF_WCHAR_STRING(rb->fgetwln_z_buffer_size));
-				}
-
-				rb->fgetwln_z_buffer[*len] = c;
-				rb->fgetwln_z_buffer[++(*len)] = 0;
-			}
-		else
-			while (!feof(f)) {
-				wint_t c;
-
-				c = fgetwc(f);
-
-				if (c == WEOF) {
-					if (*len == 0)
-						return (NULL);
-					goto line_read_done;
-				}
-				if (c == eols)
-					goto line_read_done;
-
-				if (*len + 1 >= rb->fgetwln_z_buffer_size) {
-					rb->fgetwln_z_buffer_size += 256;
-					rb->fgetwln_z_buffer = sort_realloc(rb->fgetwln_z_buffer,
-					    SIZEOF_WCHAR_STRING(rb->fgetwln_z_buffer_size));
-				}
-
-				rb->fgetwln_z_buffer[*len] = c;
-				rb->fgetwln_z_buffer[++(*len)] = 0;
-			}
-
-line_read_done:
-		/* we do not count the last 0 */
-		return (bwssbdup(rb->fgetwln_z_buffer, *len));
-	}
-}
-
 int
 bwsncmp(const struct bwstring *bws1, const struct bwstring *bws2,
     size_t offset, size_t len)
diff --git a/usr.bin/sort/file.c b/usr.bin/sort/file.c
--- a/usr.bin/sort/file.c
+++ b/usr.bin/sort/file.c
@@ -75,7 +75,7 @@
 	struct reader_buffer	 rb;
 	FILE			*file;
 	char			*fname;
-	unsigned char		*buffer;
+	char			*buffer;
 	unsigned char		*mmapaddr;
 	unsigned char		*mmapptr;
 	size_t			 bsz;
@@ -713,7 +713,7 @@
 		}
 
 	} else if (fr->file != stdin) {
-		unsigned char *strend;
+		char *strend;
 		size_t bsz1, remsz, search_start;
 
 		search_start = 0;
@@ -785,10 +785,16 @@
 		fr->strbeg = (strend - fr->buffer) + 1;
 
 	} else {
-		size_t len = 0;
-
-		ret = bwsfgetln(fr->file, &len, sort_opts_vals.zflag,
-		    &(fr->rb));
+		int delim = sort_opts_vals.zflag ? '\0' : '\n';
+		ssize_t len = getdelim(&fr->buffer, &fr->bsz, delim, fr->file);
+		if (len < 0) {
+			if (!feof(fr->file))
+				err(2, NULL);
+			return (NULL);
+		}
+		if (len > 0 && fr->buffer[len - 1] == delim)
+			len--;
+		ret = bwscsbdup(fr->buffer, len);
 	}
 
 	return (ret);