diff --git a/classes/controlledVocab/ControlledVocabDAO.inc.php b/classes/controlledVocab/ControlledVocabDAO.inc.php
index c3f1da2b732..8af609bc3c9 100644
--- a/classes/controlledVocab/ControlledVocabDAO.inc.php
+++ b/classes/controlledVocab/ControlledVocabDAO.inc.php
@@ -52,6 +52,10 @@ function getById($controlledVocabId) {
 	 * @return $controlledVocab
 	 */
 	function _build($symbolic, $assocType = 0, $assocId = 0) {
+		// Attempt to fetch an existing controlled vocabulary.
+		$controlledVocab = $this->getBySymbolic($symbolic, $assocType, $assocId);
+		if ($controlledVocab) return $controlledVocab;
+
 		// Attempt to build a new controlled vocabulary.
 		$controlledVocab = $this->newDataObject();
 		$controlledVocab->setSymbolic($symbolic);