diff --git a/MathCaptcha.class.php b/MathCaptcha.class.php
index 220df31da..5dbbeeb99 100644
--- a/MathCaptcha.class.php
+++ b/MathCaptcha.class.php
@@ -39,17 +39,11 @@ class MathCaptcha extends SimpleCaptcha {
 
 	/** Fetch the math */
 	function fetchMath( $sum ) {
-		// class_exists() unfortunately doesn't work with HipHop, and
-		// its replacement, MWInit::classExists(), wasn't added until
-		// MW 1.18, and is thus unusable here - so instead, we'll
-		// just duplicate the code of MWInit::classExists().
-		try {
-			$r = new ReflectionClass( 'MathRenderer' );
-		} catch( ReflectionException $r ) {
+		if( MWInit::classExists( 'MathRenderer' ) ){
+			$math = new MathRenderer( $sum );
+		} else {
 			throw new MWException( 'MathCaptcha requires the Math extension for MediaWiki versions 1.18 and above.' );
 		}
-
-		$math = new MathRenderer( $sum );
 		$math->setOutputMode( MW_MATH_PNG );
 		$html = $math->render();
 		return preg_replace( '/alt=".*?"/', '', $html );