diff --git a/lib/rdcu_rmap.c b/lib/rdcu_rmap.c
index 4773790055cc377706a19e4c77180ccbb6db5bdf..a1d571698fa15bd00e83803f8426d18473e47d32 100644
--- a/lib/rdcu_rmap.c
+++ b/lib/rdcu_rmap.c
@@ -684,6 +684,9 @@ int rdcu_set_return_path(uint8_t *path, uint8_t len)
 	if (len > RMAP_MAX_REPLY_PATH_LEN)
 		return -1;
 
+	if (len & 0x3)
+		return -1;	/* not a multiple of 4 */
+
 	if (!path || !len) {
 		rpath     = NULL;
 		rpath_len = 0;