diff --git a/bin/pt-online-schema-change b/bin/pt-online-schema-change
index a796074b..e55d6f5b 100755
--- a/bin/pt-online-schema-change
+++ b/bin/pt-online-schema-change
@@ -8029,14 +8029,24 @@ my $term_readkey = eval {
 use sigtrap 'handler', \&sig_int, 'normal-signals';
 
 
-
-
 my $exit_status = 0;
 my $oktorun     = 1;
 my $dont_interrupt_now = 0;
 my @drop_trigger_sqls;
 my @triggers_not_dropped;
 my $pxc_version = '0';
+# Completely ignore these error codes.
+my %ignore_code = (
+   # Error: 1592 SQLSTATE: HY000  (ER_BINLOG_UNSAFE_STATEMENT)
+   # Message: Statement may not be safe to log in statement format. 
+   # Ignore this warning because we have purposely set statement-based
+   # replication.
+   1592 => 1,
+   # Error: 1062 SQLSTATE: 23000 ( ER_DUP_ENTRY )
+   # Message: Duplicate entry '%ld' for key '%s'
+   # MariaDB 5.5.28+ has this as a warning; See https://bugs.launchpad.net/percona-toolkit/+bug/1099836
+   1062 => 1,
+);
 
 $OUTPUT_AUTOFLUSH = 1;
 
@@ -8049,6 +8059,7 @@ sub main {
    @drop_trigger_sqls    = ();
    @triggers_not_dropped = ();
    $dont_interrupt_now   = 0;
+   %ignore_code = (1592 => 1, 1062 => 1);
 
    my %stats = (
       INSERT => 0,
@@ -8062,6 +8073,10 @@ sub main {
    $o->get_specs();
    $o->get_opts();
 
+   if ( $o->get('null-to-not-null') ) {
+      $ignore_code{1048} = 1;
+   } 
+
    my $dp = $o->DSNParser();
    $dp->prop('set-vars', $o->set_vars());
 
@@ -10749,18 +10764,6 @@ sub exec_nibble {
    my $chunk       = $nibble_iter->nibble_number();
    my $chunk_index = $nibble_iter->nibble_index();
          
-   # Completely ignore these error codes.
-   my %ignore_code = (
-      # Error: 1592 SQLSTATE: HY000  (ER_BINLOG_UNSAFE_STATEMENT)
-      # Message: Statement may not be safe to log in statement format. 
-      # Ignore this warning because we have purposely set statement-based
-      # replication.
-      1592 => 1,
-      # Error: 1062 SQLSTATE: 23000 ( ER_DUP_ENTRY )
-      # Message: Duplicate entry '%ld' for key '%s'
-      # MariaDB 5.5.28+ has this as a warning; See https://bugs.launchpad.net/percona-toolkit/+bug/1099836
-      1062 => 1,
-   );
          
    # Warn once per-table for these error codes if the error message
    # matches the pattern.
@@ -11614,6 +11617,13 @@ to 10 C<_> (underscore) to find a unique table name.  If a table name is
 specified, the tool does not prefix it with C<_>, so the table must not
 exist.
 
+=item --null-to-not-null
+
+Allows MODIFYing a column that allows NULL values to one that doesn't allow
+them. The rows which contain NULL values will be converted to the defined
+default value. If no explicit DEFAULT value is given MySQL will assign a default
+value based on datatype, e.g. 0 for number datatypes, '' for string datatypes.
+
 =item --password
 
 short form: -p; type: string
diff --git a/t/pt-online-schema-change/bugs.t b/t/pt-online-schema-change/bugs.t
index 182e9f52..056e097d 100644
--- a/t/pt-online-schema-change/bugs.t
+++ b/t/pt-online-schema-change/bugs.t
@@ -38,6 +38,51 @@ my $output;
 my $exit_status;
 my $sample  = "t/pt-online-schema-change/samples/";
 
+# ############################################################################
+# https://bugs.launchpad.net/percona-toolkit/+bug/1336734
+# pt-online-schema-change 2.2.17 adds --null-to-not-null feature
+# ############################################################################
+$sb->load_file('master', "$sample/bug-1336734.sql");
+
+($output, $exit_status) = full_output(
+   sub { pt_online_schema_change::main(@args, 
+      "$master_dsn,D=test,t=lp1336734",
+      "--execute",
+      "--null-to-not-null",
+      # notice we are not using a DEFAULT value, to also
+      # test if the "default default" value for datatype
+      # is used         
+      "--alter", "MODIFY COLUMN name VARCHAR(20) NOT NULL",
+      qw(--chunk-size 2 --print)) },
+);
+
+my $test_rows = $master_dbh->selectall_arrayref("SELECT id, name FROM test.lp1336734 ORDER BY id");
+ok (!$exit_status,
+    "--null-to-not-null exit status = 0"
+);
+is_deeply(
+   $test_rows,
+  [
+     [
+       '1',
+       'curly'
+     ],
+     [
+       '2',
+       'larry'
+     ],
+     [
+       '3',
+       ''
+     ],
+     [
+       '4',
+       'moe'
+     ]
+  ],
+   "--null-to-not-null default value good"
+);
+
 # ############################################################################
 # https://bugs.launchpad.net/percona-toolkit/+bug/994002
 # pt-online-schema-change 2.1.1 doesn't choose the PRIMARY KEY
diff --git a/t/pt-online-schema-change/samples/bug-1336734.sql b/t/pt-online-schema-change/samples/bug-1336734.sql
new file mode 100644
index 00000000..93a4d847
--- /dev/null
+++ b/t/pt-online-schema-change/samples/bug-1336734.sql
@@ -0,0 +1,11 @@
+drop database if exists test;
+create database test;
+use test;
+
+CREATE TABLE lp1336734 (
+   id    int primary key,
+   name  varchar(20) DEFAULT NULL
+);
+
+INSERT INTO lp1336734 VALUES (1, "curly"), (2, "larry") , (3, NULL), (4, "moe");
+