Index: src/wp-includes/wp-db.php
===================================================================
--- src/wp-includes/wp-db.php	(revision 32260)
+++ src/wp-includes/wp-db.php	(working copy)
@@ -2542,6 +2542,7 @@
 
 					// Split the CONVERT() calls by charset, so we can make sure the connection is right
 					$queries[ $value['charset'] ][ $col ] = $this->prepare( "CONVERT( %s USING {$value['charset']} )", $value['value'] );
+					unset( $data[ $col ]['db'] );
 				}
 			}
 
Index: tests/phpunit/tests/db/charset.php
===================================================================
--- tests/phpunit/tests/db/charset.php	(revision 32260)
+++ tests/phpunit/tests/db/charset.php	(working copy)
@@ -55,19 +55,25 @@
 				'expected' => "H€llo\xf0\x9f\x98\x88World¢"
 			),
 			'koi8r' => array(
-				// koi8r is a character set that needs to be checked in MySQL
 				'charset'  => 'koi8r',
 				'value'    => "\xfdord\xf2ress",
 				'expected' => "\xfdord\xf2ress",
-				'db'       => true
 			),
 			'hebrew' => array(
-				// hebrew needs to be checked in MySQL, too
 				'charset'  => 'hebrew',
 				'value'    => "\xf9ord\xf7ress",
 				'expected' => "\xf9ord\xf7ress",
-				'db'       => true
 			),
+			'cp1251' => array(
+				'charset'  => 'cp1251',
+				'value'    => "\xd8ord\xd0ress",
+				'expected' => "\xd8ord\xd0ress",
+			),
+			'tis620' => array(
+				'charset'  => 'tis620',
+				'value'    => "\xccord\xe3ress",
+				'expected' => "\xccord\xe3ress",
+			),
 			'false' => array(
 				// false is a column with no character set (ie, a number column)
 				'charset'  => false,