diff --git a/block_class.install b/block_class.install
index 0837259..dfe7281 100644
--- a/block_class.install
+++ b/block_class.install
@@ -15,27 +15,27 @@ function block_class_schema() {
     'fields' => array(
       'module' => array(
         'type' => 'varchar',
-        'length' => '255',
+        'length' => 64,
         'not null' => TRUE,
         'default' => '',
         'description' => 'The module to which the block belongs.',
       ),
       'delta' => array(
         'type' => 'varchar',
-        'length' => '255',
+        'length' => 32,
         'not null' => TRUE,
         'default' => '',
         'description' => "The ID of the module's block.",
       ),
       'css_class' => array(
         'type' => 'varchar',
-        'length' => '255',
+        'length' => 255,
         'not null' => TRUE,
         'default' => '',
         'description' => 'String containing the classes for the block.',
       ),
     ),
-    'primary key' => array(array('module', 128), array('delta', 128)),
+    'primary key' => array('module', 'delta'),
   );
 
   return $schema;
@@ -53,7 +53,7 @@ function block_class_update_7100(&$sandbox) {
   db_change_field('block_class', 'module', 'module',
     array(
       'type' => 'varchar',
-      'length' => '255',
+      'length' => 64,
       'not null' => TRUE,
       'default' => '',
       'description' => t('The module to which the block belongs.'),
@@ -63,7 +63,7 @@ function block_class_update_7100(&$sandbox) {
   db_change_field('block_class', 'delta', 'delta',
     array(
       'type' => 'varchar',
-      'length' => '255',
+      'length' => 32,
       'not null' => TRUE,
       'default' => '',
       'description' => t("The ID of the module's block."),
@@ -73,7 +73,7 @@ function block_class_update_7100(&$sandbox) {
   db_change_field('block_class', 'css_class', 'css_class',
     array(
       'type' => 'varchar',
-      'length' => '255',
+      'length' => 255,
       'not null' => TRUE,
       'default' => '',
       'description' => t('String containing the classes for the block.'),
@@ -81,7 +81,7 @@ function block_class_update_7100(&$sandbox) {
   );
 
   // Restore the primary key.
-  db_add_primary_key('block_class', array(array('module', 128), array('delta',128)));
+  db_add_primary_key('block_class', array('module', 'delta'));
 
   return $status;
 }