diff --git a/usr.bin/diff3/diff3.c b/usr.bin/diff3/diff3.c
index c475c3d65b07..03cd24283a13 100644
--- a/usr.bin/diff3/diff3.c
+++ b/usr.bin/diff3/diff3.c
@@ -257,28 +257,16 @@ getchange(FILE *b)
 static char *
 get_line(FILE *b, size_t *n)
 {
-	char *cp;
-	size_t len;
-	static char *buf;
-	static size_t bufsize;
+	ssize_t len;
+	static char *buf = NULL;
+	static size_t bufsize = 0;
 
-	if ((cp = fgetln(b, &len)) == NULL)
+	if ((len = getline(&buf, &bufsize, b)) < 0)
 		return (NULL);
 
-	if (cp[len - 1] != '\n')
-		len++;
-	if (len + 1 > bufsize) {
-		do {
-			bufsize += 1024;
-		} while (len + 1 > bufsize);
-		if ((buf = realloc(buf, bufsize)) == NULL)
-			err(EXIT_FAILURE, NULL);
-	}
-	memcpy(buf, cp, len - 1);
-	buf[len - 1] = '\n';
-	buf[len] = '\0';
 	if (n != NULL)
 		*n = len;
+
 	return (buf);
 }