diff --git a/src/wp-includes/taxonomy.php b/src/wp-includes/taxonomy.php
index fa32393b45..6ddfeb00a2 100644
--- a/src/wp-includes/taxonomy.php
+++ b/src/wp-includes/taxonomy.php
@@ -954,7 +954,7 @@ function get_term($term, $taxonomy, $output = OBJECT, $filter = 'raw') {
  * @uses sanitize_term() Cleanses the term based on $filter context before returning.
  * @see sanitize_term_field() The $context param lists the available values for get_term_by() $filter param.
  *
- * @param string $field Either 'slug', 'name', or 'id'
+ * @param string $field Either 'slug', 'name', 'id' (term_id), or 'term_taxonomy_id'
  * @param string|int $value Search for this term value
  * @param string $taxonomy Taxonomy Name
  * @param string $output Constant OBJECT, ARRAY_A, or ARRAY_N
@@ -976,6 +976,9 @@ function get_term_by($field, $value, $taxonomy, $output = OBJECT, $filter = 'raw
 		// Assume already escaped
 		$value = wp_unslash($value);
 		$field = 't.name';
+	} else if ( 'term_taxonomy_id' == $field ) {
+		$value = (int) $value;
+		$field = 'tt.term_taxonomy_id';
 	} else {
 		$term = get_term( (int) $value, $taxonomy, $output, $filter);
 		if ( is_wp_error( $term ) )
diff --git a/tests/phpunit/tests/term.php b/tests/phpunit/tests/term.php
index ff3fd8a541..6b35f4e2f8 100644
--- a/tests/phpunit/tests/term.php
+++ b/tests/phpunit/tests/term.php
@@ -489,7 +489,7 @@ class Tests_Term extends WP_UnitTestCase {
 		$this->assertEquals( array( $term4['term_id'] ), $post->post_category );
 
 		wp_set_post_categories( $post_id, array( $term1['term_id'], $term2['term_id'] ), true );
-		$this->assertEquals( array( $term2['term_id'], $term4['term_id'],$term1['term_id'] ), $post->post_category );
+		$this->assertEquals( array( $term2['term_id'], $term4['term_id'], $term1['term_id'] ), $post->post_category );
 
 		wp_set_post_categories( $post_id, array(), true );
 		$this->assertEquals( 1, count( $post->post_category ) );
@@ -499,4 +499,10 @@ class Tests_Term extends WP_UnitTestCase {
 		$this->assertEquals( 1, count( $post->post_category ) );
 		$this->assertEquals( get_option( 'default_category' ), $post->post_category[0] );
 	}
+
+	function test_get_term_by_tt_id() {
+		$term1 = wp_insert_term( 'Foo', 'category' );
+		$term2 = get_term_by( 'term_taxonomy_id', $term1['term_taxonomy_id'], 'category' );
+		$this->assertEquals( get_term( $term1['term_id'], 'category' ), $term2 );
+	}
 }