diff --git a/net/ethtool/ts.h b/net/ethtool/ts.h
index d901a879a671..ab9805308353 100644
--- a/net/ethtool/ts.h
+++ b/net/ethtool/ts.h
@@ -5,9 +5,15 @@
 
 #include "netlink.h"
 
+/* phc_index is an int and -1 means no PHC, so keep the request non-negative */
+static const struct netlink_range_validation ethnl_ts_prov_index_range = {
+	.max = INT_MAX,
+};
+
 static const struct nla_policy
 ethnl_ts_hwtst_prov_policy[ETHTOOL_A_TS_HWTSTAMP_PROVIDER_MAX + 1] = {
-	[ETHTOOL_A_TS_HWTSTAMP_PROVIDER_INDEX] = { .type = NLA_U32 },
+	[ETHTOOL_A_TS_HWTSTAMP_PROVIDER_INDEX] =
+		NLA_POLICY_FULL_RANGE(NLA_U32, &ethnl_ts_prov_index_range),
 	[ETHTOOL_A_TS_HWTSTAMP_PROVIDER_QUALIFIER] =
 		NLA_POLICY_MAX(NLA_U32, HWTSTAMP_PROVIDER_QUALIFIER_CNT - 1)
 };