diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_erp.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_erp.c
index c1a9cc9a32923165e0af99b2a59db6cd6ed3b150..4c98950380d536ed30d146b3a6eeac9b098a1fae 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_erp.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_erp.c
@@ -1171,13 +1171,12 @@ mlxsw_sp_acl_erp_delta_fill(const struct mlxsw_sp_acl_erp_key *parent_key,
 			return -EINVAL;
 	}
 	if (si == -1) {
-		/* The masks are the same, this cannot happen.
-		 * That means the caller is broken.
+		/* The masks are the same, this can happen in case eRPs with
+		 * the same mask were created in both A-TCAM and C-TCAM.
+		 * The only possible condition under which this can happen
+		 * is identical rule insertion. Delta is not possible here.
 		 */
-		WARN_ON(1);
-		*delta_start = 0;
-		*delta_mask = 0;
-		return 0;
+		return -EINVAL;
 	}
 	pmask = (unsigned char) parent_key->mask[__MASK_IDX(si)];
 	mask = (unsigned char) key->mask[__MASK_IDX(si)];