diff --git a/CHANGES.txt b/CHANGES.txt
index 52f8ccf1e7..67b5824ce4 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -21,6 +21,7 @@
  * cqlsh: Fix handling of $$-escaped strings (CASSANDRA-12189)
  * Fix SSL JMX requiring truststore containing server cert (CASSANDRA-12109)
 Merged from 3.0:
+ * AssertionError with MVs on updating a row that isn't indexed due to a null value (CASSANDRA-12247)
  * Disable RR and speculative retry with EACH_QUORUM reads (CASSANDRA-11980)
  * Add option to override compaction space check (CASSANDRA-12180)
  * Faster startup by only scanning each directory for temporary files once (CASSANDRA-12114)
diff --git a/src/java/org/apache/cassandra/db/view/ViewUpdateGenerator.java b/src/java/org/apache/cassandra/db/view/ViewUpdateGenerator.java
index 12eb47416a..21613635ac 100644
--- a/src/java/org/apache/cassandra/db/view/ViewUpdateGenerator.java
+++ b/src/java/org/apache/cassandra/db/view/ViewUpdateGenerator.java
@@ -190,7 +190,7 @@ public class ViewUpdateGenerator
 
         // If the update didn't modified this column, the cells will be the same object so it's worth checking
         if (before == after)
-            return before == null ? UpdateAction.NONE : UpdateAction.UPDATE_EXISTING;
+            return isLive(before) ? UpdateAction.UPDATE_EXISTING : UpdateAction.NONE;
 
         if (!isLive(before))
             return isLive(after) ? UpdateAction.NEW_ENTRY : UpdateAction.NONE;
@@ -451,7 +451,7 @@ public class ViewUpdateGenerator
 
         ColumnDefinition baseColumn = view.baseNonPKColumnsInViewPK.get(0);
         Cell cell = baseRow.getCell(baseColumn);
-        assert isLive(cell) : "We shouldn't have got there is the base row had no associated entry";
+        assert isLive(cell) : "We shouldn't have got there if the base row had no associated entry";
 
         long timestamp = Math.max(baseLiveness.timestamp(), cell.timestamp());
         return LivenessInfo.withExpirationTime(timestamp, cell.ttl(), cell.localDeletionTime());
diff --git a/test/unit/org/apache/cassandra/cql3/ViewTest.java b/test/unit/org/apache/cassandra/cql3/ViewTest.java
index 85f01a6de5..c9ef401e23 100644
--- a/test/unit/org/apache/cassandra/cql3/ViewTest.java
+++ b/test/unit/org/apache/cassandra/cql3/ViewTest.java
@@ -1108,4 +1108,33 @@ public class ViewTest extends CQLTester
         }
 
     }
+
+    @Test
+    public void testNullInClusteringColumns() throws Throwable
+    {
+        createTable("CREATE TABLE %s (id1 int, id2 int, v1 text, v2 text, PRIMARY KEY (id1, id2))");
+
+        executeNet(protocolVersion, "USE " + keyspace());
+
+        createView("mv",
+                   "CREATE MATERIALIZED VIEW %s AS" +
+                   "  SELECT id1, v1, id2, v2" +
+                   "  FROM %%s" +
+                   "  WHERE id1 IS NOT NULL AND v1 IS NOT NULL AND id2 IS NOT NULL" +
+                   "  PRIMARY KEY (id1, v1, id2)" +
+                   "  WITH CLUSTERING ORDER BY (v1 DESC, id2 ASC)");
+
+        execute("INSERT INTO %s (id1, id2, v1, v2) VALUES (?, ?, ?, ?)", 0, 1, "foo", "bar");
+
+        assertRowsNet(protocolVersion, executeNet(protocolVersion, "SELECT * FROM %s"), row(0, 1, "foo", "bar"));
+        assertRowsNet(protocolVersion, executeNet(protocolVersion, "SELECT * FROM mv"), row(0, "foo", 1, "bar"));
+
+        executeNet(protocolVersion, "UPDATE %s SET v1=? WHERE id1=? AND id2=?", null, 0, 1);
+        assertRowsNet(protocolVersion, executeNet(protocolVersion, "SELECT * FROM %s"), row(0, 1, null, "bar"));
+        assertRowsNet(protocolVersion, executeNet(protocolVersion, "SELECT * FROM mv"));
+
+        executeNet(protocolVersion, "UPDATE %s SET v2=? WHERE id1=? AND id2=?", "rab", 0, 1);
+        assertRowsNet(protocolVersion, executeNet(protocolVersion, "SELECT * FROM %s"), row(0, 1, null, "rab"));
+        assertRowsNet(protocolVersion, executeNet(protocolVersion, "SELECT * FROM mv"));
+    }
 }