diff --git a/includes/Parser/FilterEvaluator.php b/includes/Parser/FilterEvaluator.php
index dec3adc13..32e54cda3 100644
--- a/includes/Parser/FilterEvaluator.php
+++ b/includes/Parser/FilterEvaluator.php
@@ -450,17 +450,10 @@ class FilterEvaluator {
 	 * and saved to self::usedVars to be returned to the caller in this function.
 	 *
 	 * @param string $filter
-	 * @return array
+	 * @return string[]
 	 */
 	public function getUsedVars( string $filter ): array {
-		$this->resetState();
-		$cachedAllowShort = $this->mAllowShort;
-		try {
-			$this->mAllowShort = false;
-			$this->evaluateExpression( $filter );
-		} finally {
-			$this->mAllowShort = $cachedAllowShort;
-		}
+		$this->checkSyntax( $filter );
 		return array_unique( $this->usedVars );
 	}
 
diff --git a/tests/phpunit/unit/Parser/ParserTest.php b/tests/phpunit/unit/Parser/ParserTest.php
index f7ed30e99..fd99e9a3c 100644
--- a/tests/phpunit/unit/Parser/ParserTest.php
+++ b/tests/phpunit/unit/Parser/ParserTest.php
@@ -1163,20 +1163,19 @@ class ParserTest extends ParserTestCase {
 		$this->assertSame( $vars, $wrapper->mVariables );
 	}
 
+	public static function provideGetUsedVars() {
+		yield [ [ 'action', 'user_name' ], 'action = "edit" & ip_in_range( user_name, "1.2.3.4" )' ];
+		yield [ [ 'action', 'user_name' ], 'action = "edit" & ip_in_range( USER_NAME, "1.2.3.4" )' ];
+		yield [ [ 'added_lines' ], "added_lines[0] !== ''" ];
+		yield [ [ 'old_size', 'new_size' ], 'old_size > 0 & new_size / old_size < 0.5' ];
+	}
+
 	/**
 	 * @covers \MediaWiki\Extension\AbuseFilter\Parser\FilterEvaluator
+	 * @dataProvider provideGetUsedVars
 	 */
-	public function testGetUsedVars() {
+	public function testGetUsedVars( $expected, $conditions ) {
 		$parser = $this->getParser();
-		/** @var FilterEvaluator $wrapper */
-		$wrapper = TestingAccessWrapper::newFromObject( $parser );
-		$this->assertSame(
-			[ 'action', 'user_name' ],
-			$wrapper->getUsedVars( 'action = "edit" & ip_in_range( user_name, "1.2.3.4" )' )
-		);
-		$this->assertSame(
-			[ 'action', 'user_name' ],
-			$wrapper->getUsedVars( 'action = "edit" & ip_in_range( USER_NAME, "1.2.3.4" )' )
-		);
+		$this->assertSame( $expected, $parser->getUsedVars( $conditions ) );
 	}
 }