diff --git a/.phpcs.xml b/.phpcs.xml
index 5e197436c..85b76d828 100644
--- a/.phpcs.xml
+++ b/.phpcs.xml
@@ -5,7 +5,6 @@
 		<exclude name="MediaWiki.Commenting.FunctionComment.MissingDocumentationProtected" />
 		<exclude name="MediaWiki.Commenting.FunctionComment.MissingDocumentationPublic" />
 		<exclude name="MediaWiki.Usage.ExtendClassUsage.FunctionConfigUsage" />
-		<exclude name="MediaWiki.Usage.ExtendClassUsage.FunctionVarUsage" />
 		<exclude name="MediaWiki.WhiteSpace.SpaceBeforeSingleLineComment.NewLineComment" />
 	</rule>
 	<file>.</file>
diff --git a/src/SpecialMathWikibase.php b/src/SpecialMathWikibase.php
index 97859dd47..cf191e9fb 100644
--- a/src/SpecialMathWikibase.php
+++ b/src/SpecialMathWikibase.php
@@ -37,7 +37,7 @@ class SpecialMathWikibase extends SpecialPage {
 				$this->getPlainText( 'math-wikibase-special-error-header' )
 			);
 			$out->addHTML(
-				wfMessage( 'math-wikibase-special-error-no-wikibase' )->inContentLanguage()->parse()
+				$this->msg( 'math-wikibase-special-error-no-wikibase' )->inContentLanguage()->parse()
 			);
 			return;
 		}
@@ -122,14 +122,14 @@ class SpecialMathWikibase extends SpecialPage {
 		if ( $e instanceof InvalidArgumentException ) {
 			$this->logger->warning( "An invalid ID was specified. Reason: " . $e->getMessage() );
 			$this->getOutput()->addHTML(
-				wfMessage( 'math-wikibase-special-error-invalid-argument' )->inContentLanguage()->parse()
+				$this->msg( 'math-wikibase-special-error-invalid-argument' )->inContentLanguage()->parse()
 			);
 		} else {
 			$this->logger->error( "An unknown error occurred while fetching data from Wikibase.", [
 				'exception' => $e
 			] );
 			$this->getOutput()->addHTML(
-				wfMessage( 'math-wikibase-special-error-unknown' )->inContentLanguage()->parse()
+				$this->msg( 'math-wikibase-special-error-unknown' )->inContentLanguage()->parse()
 			);
 		}
 	}
@@ -140,7 +140,7 @@ class SpecialMathWikibase extends SpecialPage {
 	 * @return string the plain text in current content language
 	 */
 	private function getPlainText( $key ) {
-		return wfMessage( $key )->inContentLanguage()->plain();
+		return $this->msg( $key )->inContentLanguage()->plain();
 	}
 
 	/**