diff --git a/bin/pt-online-schema-change b/bin/pt-online-schema-change
index ccd4e7cb..295964c7 100755
--- a/bin/pt-online-schema-change
+++ b/bin/pt-online-schema-change
@@ -10215,6 +10215,8 @@ sub create_new_table {
       );
       my $constraint_pattern = qr((CONSTRAINT `__|CONSTRAINT `_|CONSTRAINT `));
       $sql =~ s/$constraint_pattern/$search_dict{$1}/gm;
+      # Limit constraint name to 64 characters
+      $sql =~ s/CONSTRAINT `([^`]{1,64})[^`]*` (.*)/  CONSTRAINT `$1` $2/gm;
 
       if ( $o->get('default-engine') ) {
          $sql =~ s/\s+ENGINE=\S+//;
diff --git a/t/pt-online-schema-change/long_fk_constraints.t b/t/pt-online-schema-change/long_fk_constraints.t
new file mode 100644
index 00000000..1ef52ed8
--- /dev/null
+++ b/t/pt-online-schema-change/long_fk_constraints.t
@@ -0,0 +1,75 @@
+#!/usr/bin/env perl
+
+BEGIN {
+   die "The PERCONA_TOOLKIT_BRANCH environment variable is not set.\n"
+      unless $ENV{PERCONA_TOOLKIT_BRANCH} && -d $ENV{PERCONA_TOOLKIT_BRANCH};
+   unshift @INC, "$ENV{PERCONA_TOOLKIT_BRANCH}/lib";
+};
+
+use strict;
+use warnings FATAL => 'all';
+use English qw(-no_match_vars);
+use Test::More;
+
+use Data::Dumper;
+use PerconaTest;
+use Sandbox;
+
+require "$trunk/bin/pt-online-schema-change";
+
+my $dp = new DSNParser(opts=>$dsn_opts);
+my $sb = new Sandbox(basedir => '/tmp', DSNParser => $dp);
+my $master_dbh = $sb->get_dbh_for('master');
+
+if ( !$master_dbh ) {
+   plan skip_all => 'Cannot connect to sandbox master';
+}
+
+# The sandbox servers run with lock_wait_timeout=3 and it's not dynamic
+# so we need to specify --set-vars innodb_lock_wait_timeout-3 else the
+# tool will die.
+my $master_dsn = 'h=127.1,P=12345,u=msandbox,p=msandbox';
+my @args       = (qw(--set-vars innodb_lock_wait_timeout=3 --alter-foreign-keys-method rebuild_constraints));
+my $output;
+my $exit_status;
+my $sample  = "t/pt-online-schema-change/samples/";
+
+# ############################################################################
+# https://bugs.launchpad.net/percona-toolkit/+bug/1215587 
+# Adding _ to constraints can create issues with constraint name length
+# ############################################################################
+
+$sb->load_file('master', "$sample/long_fk_constraints.sql");
+
+# run once: we expect constraint names to be prefixed with one underscore
+# if they havre't one, and to remove 2 if they have 2
+($output, $exit_status) = full_output(
+   sub { pt_online_schema_change::main(@args,
+      "$master_dsn,D=bug1215587,t=Table1",
+      "--alter", "ENGINE=InnoDB",
+      qw(--execute)) },
+);
+
+warn $output;
+
+my $constraints = $master_dbh->selectall_arrayref("SELECT TABLE_NAME, CONSTRAINT_NAME FROM information_schema.KEY_COLUMN_USAGE WHERE table_schema='bug1215587' and (TABLE_NAME='Table1' OR TABLE_NAME='Table2') and CONSTRAINT_NAME LIKE '%fkey%' ORDER BY TABLE_NAME, CONSTRAINT_NAME"); 
+
+warn Data::Dumper::Dumper($constraints);
+
+is_deeply(
+   $constraints,
+   [
+    [ 'Table1', '__fkey1a' ],
+    [ 'Table1', '__fkey_SALES_RECURRING_PROFILE_CUSTOMER_CUSTOMER_ENTITY_ENTITY_I' ],
+    [ 'Table2', '_fkey2a' ],
+    [ 'Table2', '__fkey2b' ]
+   ],
+   "First run adds or removes underscore from constraint names, accordingly"
+);
+
+# #############################################################################
+# Done.
+# #############################################################################
+$sb->wipe_clean($master_dbh);
+ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
+done_testing;
diff --git a/t/pt-online-schema-change/samples/long_fk_constraints.sql b/t/pt-online-schema-change/samples/long_fk_constraints.sql
new file mode 100644
index 00000000..cbc5811d
--- /dev/null
+++ b/t/pt-online-schema-change/samples/long_fk_constraints.sql
@@ -0,0 +1,28 @@
+/* ----- Create two test tables with FKs for scenario 1 and 2: ----- */
+drop database if exists bug1215587;
+CREATE DATABASE bug1215587;
+USE bug1215587;
+
+CREATE TABLE IF NOT EXISTS `Table1` (
+  `ID` int unsigned NOT NULL AUTO_INCREMENT,
+  `T2ID` smallint unsigned DEFAULT NULL,
+  PRIMARY KEY (`ID`),
+  KEY `tagIndex` (`T2ID`)
+) ENGINE=InnoDB DEFAULT CHARSET=latin1;
+
+CREATE TABLE `Table2` (
+  `ID` smallint unsigned NOT NULL AUTO_INCREMENT,
+  PRIMARY KEY (`ID`)
+) ENGINE=InnoDB DEFAULT CHARSET=latin1;
+
+ALTER TABLE `Table1`
+  ADD CONSTRAINT `_fkey1a` FOREIGN KEY (`T2ID`) REFERENCES `Table2` (`ID`) ON DELETE NO ACTION;
+
+ALTER TABLE `Table1`
+  ADD CONSTRAINT `_fkey_SALES_RECURRING_PROFILE_CUSTOMER_CUSTOMER_ENTITY_ENTITY_ID` FOREIGN KEY (`T2ID`) REFERENCES `Table2` (`ID`) ON DELETE NO ACTION;
+
+ALTER TABLE `Table2`
+  ADD CONSTRAINT `fkey2a` FOREIGN KEY (`ID`) REFERENCES `Table1` (`T2ID`) ON DELETE NO ACTION;
+
+ALTER TABLE `Table2`
+  ADD CONSTRAINT `_fkey2b` FOREIGN KEY (`ID`) REFERENCES `Table1` (`T2ID`) ON DELETE NO ACTION;