diff --git a/sys/net/gnrc/network_layer/ipv6/nib/nib.c b/sys/net/gnrc/network_layer/ipv6/nib/nib.c
index 3195d62f63..6c9225018c 100644
--- a/sys/net/gnrc/network_layer/ipv6/nib/nib.c
+++ b/sys/net/gnrc/network_layer/ipv6/nib/nib.c
@@ -1621,7 +1621,9 @@ static uint32_t _handle_pio(gnrc_netif_t *netif, const icmpv6_hdr_t *icmpv6,
     valid_ltime = byteorder_ntohl(pio->valid_ltime);
     pref_ltime = byteorder_ntohl(pio->pref_ltime);
     if ((pio->len != NDP_OPT_PI_LEN) || (icmpv6->type != ICMPV6_RTR_ADV) ||
-        ipv6_addr_is_link_local(&pio->prefix) || (valid_ltime < pref_ltime)) {
+        ipv6_addr_is_link_local(&pio->prefix) || (valid_ltime < pref_ltime) ||
+        /* https://datatracker.ietf.org/doc/html/rfc6775#section-5.4 */
+        (gnrc_netif_is_6ln(netif) && (pio->flags & NDP_OPT_PI_FLAGS_L))) {
         DEBUG("nib: ignoring PIO with invalid data\n");
         return UINT32_MAX;
     }
diff --git a/tests/net/gnrc_ipv6_nib_6ln/main.c b/tests/net/gnrc_ipv6_nib_6ln/main.c
index eaa13747ac..96aa995e05 100644
--- a/tests/net/gnrc_ipv6_nib_6ln/main.c
+++ b/tests/net/gnrc_ipv6_nib_6ln/main.c
@@ -1056,6 +1056,12 @@ static void test_handle_pkt__rtr_adv__success(uint8_t rtr_adv_flags,
         TEST_ASSERT_EQUAL_INT(exp_netif.mtu, _mock_netif->ipv6.mtu);
     }
     state = NULL;
+    if (pio_flags & NDP_OPT_PI_FLAGS_L) {
+        pio = false;
+        /* Should the host erroneously receive a PIO with the L (on-link) flag set,
+         * then that PIO MUST be ignored.
+         * - https://datatracker.ietf.org/doc/html/rfc6775#section-5.4 */
+    }
     if (pio) {
         if (pio_flags & NDP_OPT_PI_FLAGS_A) {
             TEST_ASSERT_MESSAGE(gnrc_netif_ipv6_addr_idx(_mock_netif,