diff --git a/sshsig.c b/sshsig.c
index 773613462..1e3b63982 100644
--- a/sshsig.c
+++ b/sshsig.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshsig.c,v 1.28 2022/02/01 23:34:47 djm Exp $ */
+/* $OpenBSD: sshsig.c,v 1.29 2022/03/30 04:27:51 djm Exp $ */
 /*
  * Copyright (c) 2019 Google LLC
  *
@@ -739,7 +739,7 @@ parse_principals_key_and_options(const char *path, u_long linenum, char *line,
 		return SSH_ERR_KEY_NOT_FOUND; /* blank or all-comment line */
 
 	/* format: identity[,identity...] [option[,option...]] key */
-	if ((tmp = strdelimw(&cp)) == NULL) {
+	if ((tmp = strdelimw(&cp)) == NULL || cp == NULL) {
 		error("%s:%lu: invalid line", path, linenum);
 		r = SSH_ERR_INVALID_FORMAT;
 		goto out;
@@ -777,6 +777,11 @@ parse_principals_key_and_options(const char *path, u_long linenum, char *line,
 			r = SSH_ERR_INVALID_FORMAT;
 			goto out;
 		}
+		if (cp == NULL || *cp == '\0') {
+			error("%s:%lu: missing key", path, linenum);
+			r = SSH_ERR_INVALID_FORMAT;
+			goto out;
+		}
 		*cp++ = '\0';
 		skip_space(&cp);
 		if (sshkey_read(key, &cp) != 0) {