diff --git a/source4/dsdb/samdb/ldb_modules/samldb.c b/source4/dsdb/samdb/ldb_modules/samldb.c
index 91e9625bf40..b9b57db8882 100644
--- a/source4/dsdb/samdb/ldb_modules/samldb.c
+++ b/source4/dsdb/samdb/ldb_modules/samldb.c
@@ -2753,6 +2753,17 @@ static int check_address_roundtrip(const char *address, int family,
 	if (strcasecmp(address, address_redux) != 0){
 		DBG_INFO("Address %s round trips to %s; fail!\n",
 			 address, address_redux);
+		/* If the address family is IPv6, and the address is in a
+		   certain range
+
+		 */
+		if (strchr(address_redux, '.') != NULL){
+			DEBUG(0, ("The IPv6 address '%s' has the misfortune of "
+				  "lying in a range that was once used for "
+				  "IPv4 embedding (that is, it might also be "
+				  "represented as '%s').\n", address,
+				  address_redux));
+		}
 		return -1;
 	}
 	return 0;
diff --git a/source4/dsdb/tests/python/sites.py b/source4/dsdb/tests/python/sites.py
index 1714ff814c7..acbf1c126f8 100755
--- a/source4/dsdb/tests/python/sites.py
+++ b/source4/dsdb/tests/python/sites.py
@@ -301,7 +301,33 @@ class SimpleSubnetTests(SitesBaseTests):
             # IP4 embedded - rejected
             "a::10.0.0.0/120",
             "a::10.9.8.7/128",
+
+            # The next ones tinker indirectly with IPv4 embedding,
+            # where Windows has some odd behaviour.
+            #
+            # Samba's libreplace inet_ntop6 expects IPv4 embedding
+            # with addresses in these forms:
+            #
+            #     ::wx:yz
+            #     ::FFFF:wx:yz
+            #
+            # these will be stringified with trailing dottted decimal, thus:
+            #
+            #     ::w.x.y.z
+            #     ::ffff:w.x.y.z
+            #
+            # and this will cause the address to be rejected by Samba,
+            # because it uses a inet_pton / inet_ntop round trip to
+            # ascertain correctness.
+
             "::ffff:0:0/96", #this one fails on WIN2012r2
+            "::ffff:aaaa:a000/120",
+            "::ffff:10:0/120",
+            "::ffff:2:300/120",
+            "::3:0/120",
+            "::2:30/124",
+            "::ffff:2:30/124",
+
             # completely wrong
             None,
             "bob",
@@ -443,6 +469,12 @@ class SimpleSubnetTests(SitesBaseTests):
             "10:0:0:42::/64",
             "1::4:5:0:0:8/127",
             "2001:db8:0:1:1:1:1:1/128",
+
+            # The "well-known prefix" 64::ff9b is another IPv4
+            # embedding scheme. Let's try that.
+            "64:ff9b::aaaa:aaaa/127",
+            "64:ff9b::/120",
+            "64:ff9b::ffff:2:3/128",
         ]
         failures = []