diff --git a/CHANGELOG b/CHANGELOG
index 9f542df..82572f7 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -47,6 +47,7 @@
 - pass root length to mount_fullpath().
 - remove unused function master_submount_list_empty().
 - move amd mounts removal into lib/mounts.c.
+- check for offset with no mount location.
 
 xx/xx/2018 autofs-5.1.5
 - fix flag file permission.
diff --git a/modules/parse_sun.c b/modules/parse_sun.c
index 43233ca..13f449e 100644
--- a/modules/parse_sun.c
+++ b/modules/parse_sun.c
@@ -803,7 +803,20 @@ update_offset_entry(struct autofs_point *ap,
 
 	memset(m_mapent, 0, MAPENT_MAX_LEN + 1);
 
-	/* Internal hosts map may have loc == NULL */
+	if (!loc || !*loc) {
+		const char *type = ap->entry->maps->type;
+
+		/* If it's not the internal hosts map it must have a
+		 * mount location.
+		 */
+		if (!type || strcmp(type, "hosts")) {
+			error(ap->logopt,
+			      MODPREFIX "syntax error in offset %s -> %s",
+			      m_offset, loc);
+			return CHE_FAIL;
+		}
+	}
+
 	if (!*m_offset) {
 		error(ap->logopt,
 		      MODPREFIX "syntax error in offset %s -> %s", m_offset, loc);