diff --git a/CHANGES.txt b/CHANGES.txt
index 5be7e1ff40..9c595fccfc 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -4,7 +4,7 @@
  * Duplicate the buffer before passing it to analyser in SASI operation (CASSANDRA-13512)
  * Properly evict pstmts from prepared statements cache (CASSANDRA-13641)
 Merged from 3.0:
-3.0.15
+ * Fix invalid writetime for null cells (CASSANDRA-13711)
  * Fix ALTER TABLE statement to atomically propagate changes to the table and its MVs (CASSANDRA-12952)
  * Fixed ambiguous output of nodetool tablestats command (CASSANDRA-13722)
  * Fix Digest mismatch Exception if hints file has UnknownColumnFamily (CASSANDRA-13696)
diff --git a/src/java/org/apache/cassandra/cql3/selection/Selection.java b/src/java/org/apache/cassandra/cql3/selection/Selection.java
index 4ea1071789..428634c177 100644
--- a/src/java/org/apache/cassandra/cql3/selection/Selection.java
+++ b/src/java/org/apache/cassandra/cql3/selection/Selection.java
@@ -404,6 +404,12 @@ public abstract class Selection
                 }
             }
             current = new ArrayList<>(columns.size());
+
+            // Timestamps and TTLs are arrays per row, we must null them out between rows
+            if (timestamps != null)
+                Arrays.fill(timestamps, Long.MIN_VALUE);
+            if (ttls != null)
+                Arrays.fill(ttls, -1);
         }
 
         /**
diff --git a/test/unit/org/apache/cassandra/cql3/validation/entities/TimestampTest.java b/test/unit/org/apache/cassandra/cql3/validation/entities/TimestampTest.java
index 3e70cd06e5..b41163c424 100644
--- a/test/unit/org/apache/cassandra/cql3/validation/entities/TimestampTest.java
+++ b/test/unit/org/apache/cassandra/cql3/validation/entities/TimestampTest.java
@@ -152,4 +152,33 @@ public class TimestampTest extends CQLTester
         execute("INSERT INTO %s (k, i) VALUES (1, 1) USING TIMESTAMP ?", unset()); // treat as 'now'
     }
 
+    @Test
+    public void testTimestampsOnUnsetColumns() throws Throwable
+    {
+        createTable("CREATE TABLE %s (k int PRIMARY KEY, i int)");
+        execute("INSERT INTO %s (k, i) VALUES (1, 1) USING TIMESTAMP 1;");
+        execute("INSERT INTO %s (k) VALUES (2) USING TIMESTAMP 2;");
+        execute("INSERT INTO %s (k, i) VALUES (3, 3) USING TIMESTAMP 1;");
+        assertRows(execute("SELECT k, i, writetime(i) FROM %s "),
+                   row(1, 1, 1L),
+                   row(2, null, null),
+                   row(3, 3, 1L));
+    }
+
+    @Test
+    public void testTimestampsOnUnsetColumnsWide() throws Throwable
+    {
+        createTable("CREATE TABLE %s (k int , c int, i int, PRIMARY KEY (k, c))");
+        execute("INSERT INTO %s (k, c, i) VALUES (1, 1, 1) USING TIMESTAMP 1;");
+        execute("INSERT INTO %s (k, c) VALUES (1, 2) USING TIMESTAMP 1;");
+        execute("INSERT INTO %s (k, c, i) VALUES (1, 3, 1) USING TIMESTAMP 1;");
+        execute("INSERT INTO %s (k, c) VALUES (2, 2) USING TIMESTAMP 2;");
+        execute("INSERT INTO %s (k, c, i) VALUES (3, 3, 3) USING TIMESTAMP 1;");
+        assertRows(execute("SELECT k, c, i, writetime(i) FROM %s "),
+                   row(1, 1, 1, 1L),
+                   row(1, 2, null, null),
+                   row(1, 3, 1, 1L),
+                   row(2, 2, null, null),
+                   row(3, 3, 3, 1L));
+    }
 }
diff --git a/test/unit/org/apache/cassandra/cql3/validation/operations/SelectTest.java b/test/unit/org/apache/cassandra/cql3/validation/operations/SelectTest.java
index 9a24bd0d7d..7c6c589798 100644
--- a/test/unit/org/apache/cassandra/cql3/validation/operations/SelectTest.java
+++ b/test/unit/org/apache/cassandra/cql3/validation/operations/SelectTest.java
@@ -4738,4 +4738,32 @@ public class SelectTest extends CQLTester
             assertRows(execute("SELECT k, v FROM %s WHERE k = 0 AND m CONTAINS KEY 'c' ALLOW FILTERING"), row(0, 2));
         });
     }
+
+    @Test
+    public void testMixedTTLOnColumns() throws Throwable
+    {
+        createTable("CREATE TABLE %s (k int PRIMARY KEY, i int)");
+        execute("INSERT INTO %s (k) VALUES (2);");
+        execute("INSERT INTO %s (k, i) VALUES (1, 1) USING TTL 100;");
+        execute("INSERT INTO %s (k, i) VALUES (3, 3) USING TTL 100;");
+        assertRows(execute("SELECT k, i, TTL(i) FROM %s "),
+                   row(1, 1, 100), row(2, null, null), row(3, 3, 100));
+    }
+
+    @Test
+    public void testMixedTTLOnColumnsWide() throws Throwable
+    {
+        createTable("CREATE TABLE %s (k int, c int, i int, PRIMARY KEY (k, c))");
+        execute("INSERT INTO %s (k, c) VALUES (2, 2);");
+        execute("INSERT INTO %s (k, c, i) VALUES (1, 1, 1) USING TTL 100;");
+        execute("INSERT INTO %s (k, c) VALUES (1, 2) ;");
+        execute("INSERT INTO %s (k, c, i) VALUES (1, 3, 3) USING TTL 100;");
+        execute("INSERT INTO %s (k, c, i) VALUES (3, 3, 3) USING TTL 100;");
+        assertRows(execute("SELECT k, c, i, TTL(i) FROM %s "),
+                   row(1, 1, 1, 100),
+                   row(1, 2, null, null),
+                   row(1, 3, 3, 100),
+                   row(2, 2, null, null),
+                   row(3, 3, 3, 100));
+    }
 }