diff --git a/code/TagField.php b/code/TagField.php
index fd6ca27..365d4c4 100644
--- a/code/TagField.php
+++ b/code/TagField.php
@@ -332,13 +332,11 @@ class TagField extends DropdownField {
 		 */
 		$source = $this->getSource();
 
-		$dataClass = $source->dataClass();
-
 		$titleField = $this->getTitleField();
 
 		$term = Convert::raw2sql($term);
 
-		$query = $dataClass::get()
+		$query = $source
 			->filter($titleField . ':PartialMatch:nocase', $term)
 			->sort($titleField)
 			->limit($this->getLazyLoadItemLimit());
diff --git a/tests/TagFieldTest.php b/tests/TagFieldTest.php
index ecc9620..0012906 100755
--- a/tests/TagFieldTest.php
+++ b/tests/TagFieldTest.php
@@ -147,6 +147,44 @@ class TagFieldTest extends SapphireTest {
 		);
 	}
 
+	/**
+	 * Tests that TagField supports pre-filtered data sources
+	 */
+	public function testRestrictedSuggestions() {
+		$source = TagFieldTestBlogTag::get()->exclude('Title', 'Tag2');
+		$field = new TagField('Tags', '', $source);
+
+		/**
+		 * Partial tag title match.
+		 */
+		$request = $this->getNewRequest(array('term' => 'Tag'));
+
+		$this->assertEquals(
+			'{"items":[{"id":1,"text":"Tag1"}]}',
+			$field->suggest($request)->getBody()
+		);
+
+		/**
+		 * Exact tag title match.
+		 */
+		$request = $this->getNewRequest(array('term' => 'Tag1'));
+
+		$this->assertEquals(
+			'{"items":[{"id":1,"text":"Tag1"}]}',
+			$field->suggest($request)->getBody()
+		);
+
+		/**
+		 * Excluded item doesn't appear in matches
+		 */
+		$request = $this->getNewRequest(array('term' => 'Tag2'));
+
+		$this->assertEquals(
+			'{"items":[]}',
+			$field->suggest($request)->getBody()
+		);
+	}
+
 	/**
 	 * @param array $parameters
 	 *