diff --git a/core/modules/migrate_drupal/config/install/migrate.migration.d6_user.yml b/core/modules/migrate_drupal/config/install/migrate.migration.d6_user.yml
index c1b9f27..33850c8 100644
--- a/core/modules/migrate_drupal/config/install/migrate.migration.d6_user.yml
+++ b/core/modules/migrate_drupal/config/install/migrate.migration.d6_user.yml
@@ -22,10 +22,21 @@ process:
     source: roles
   signature: signature
   signature_format:
-    plugin: migration
-    migration: d6_filter_format
-    source: signature_format
-    no_stub: 1
+    -
+# Drupal 6 stores 0 as the signature format when signatures are disabled.
+# Drupal 8 stores a NULL.
+      plugin: static_map
+      bypass: true
+      source: signature_format
+      map:
+        0: NULL
+    -
+# Do not try to migrate the NULL format.
+      plugin: skip_process_on_empty
+    -
+      plugin: migration
+      migration: d6_filter_format
+      no_stub: 1
   user_picture:
     plugin: d6_user_picture
     source: uid
diff --git a/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/Dump/Drupal6User.php b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/Dump/Drupal6User.php
index 2b662e8..e275572 100644
--- a/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/Dump/Drupal6User.php
+++ b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/Dump/Drupal6User.php
@@ -377,6 +377,56 @@ public static function getData($table) {
           'pass_plain' => 'joe.bloggs_pass',
           'expected_timezone' => NULL,
         ),
+        array(
+          'uid' => 16,
+          'name' => 'sal.saraniti',
+          'pass' => md5('sal.saraniti'),
+          'mail' => 'sal.saraniti@example.com',
+          'picture' => '',
+          'mode' => 0,
+          'sort' => 0,
+          'threshold' => 0,
+          'theme' => '',
+          'signature' => '',
+          'signature_format' => 0,
+          'created' => 1391151054,
+          'access' => 1391259574,
+          'login' => 1391162255,
+          'status' => 1,
+          'timezone' => '3600',
+          'language' => 'en',
+          'init' => 'sal.saraniti@example.com',
+          'data' => serialize(array()),
+          'timezone_name' => NULL,
+          'timezone_id' => 0,
+          'pass_plain' => 'sal.saraniti',
+          'expected_timezone' => NULL,
+        ),
+        array(
+          'uid' => 17,
+          'name' => 'terry.saraniti',
+          'pass' => md5('terry.saraniti'),
+          'mail' => 'terry.saraniti@example.com',
+          'picture' => '',
+          'mode' => 0,
+          'sort' => 0,
+          'threshold' => 0,
+          'theme' => '',
+          'signature' => '',
+          'signature_format' => 0,
+          'created' => 1390151054,
+          'access' => 1390259574,
+          'login' => 1390162255,
+          'status' => 1,
+          'timezone' => '3600',
+          'language' => 'en',
+          'init' => 'terry.saraniti@example.com',
+          'data' => serialize(array()),
+          'timezone_name' => NULL,
+          'timezone_id' => 0,
+          'pass_plain' => 'terry.saraniti',
+          'expected_timezone' => NULL,
+        ),
       ),
       'users_roles' => array(
         array('uid' => 2, 'rid' => 3),
@@ -385,6 +435,9 @@ public static function getData($table) {
         array('uid' => 15, 'rid' => 3),
         array('uid' => 15, 'rid' => 4),
         array('uid' => 15, 'rid' => 5),
+        array('uid' => 16, 'rid' => 3),
+        array('uid' => 16, 'rid' => 5),
+        array('uid' => 17, 'rid' => 4),
       ),
       'event_timezones' => array(
         array(
@@ -414,6 +467,20 @@ public static function getData($table) {
         array('fid' => 12, 'uid' => 15, 'value' => "ABBA\nBoney M"),
         array('fid' => 13, 'uid' => 15, 'value' => "http://example.com/journal"),
         array('fid' => 14, 'uid' => 15, 'value' => 'a:3:{s:5:"month";s:2:"11";s:3:"day";s:2:"25";s:4:"year";s:4:"1982";}'),
+        array('fid' => 8, 'uid' => 16, 'value' => 'blue'),
+        array('fid' => 9, 'uid' => 16, 'value' => 'Pellentesque sit amet sem et purus pretium consectetuer.'),
+        array('fid' => 10, 'uid' => 16, 'value' => '0'),
+        array('fid' => 11, 'uid' => 16, 'value' => 'Faithful servant'),
+        array('fid' => 12, 'uid' => 16, 'value' => "Van Halen\nDave M"),
+        array('fid' => 13, 'uid' => 16, 'value' => "http://example.com/monkeys"),
+        array('fid' => 14, 'uid' => 16, 'value' => 'a:3:{s:5:"month";s:1:"9";s:3:"day";s:2:"23";s:4:"year";s:4:"1939";}'),
+        array('fid' => 8, 'uid' => 17, 'value' => 'yellow'),
+        array('fid' => 9, 'uid' => 17, 'value' => 'The quick brown fox jumped over the lazy dog.'),
+        array('fid' => 10, 'uid' => 17, 'value' => '0'),
+        array('fid' => 11, 'uid' => 17, 'value' => 'Anonymous donor'),
+        array('fid' => 12, 'uid' => 17, 'value' => "Toto\nJohn Denver"),
+        array('fid' => 13, 'uid' => 17, 'value' => "http://example.com/penguins"),
+        array('fid' => 14, 'uid' => 17, 'value' => 'a:3:{s:5:"month";s:2:"12";s:3:"day";s:2:"18";s:4:"year";s:4:"1942";}'),
       ),
     );