diff --git a/MathLaTeXML.php b/MathLaTeXML.php
index 765342e..d5ae368 100644
--- a/MathLaTeXML.php
+++ b/MathLaTeXML.php
@@ -116,8 +116,10 @@ class MathLaTeXML extends MathMathML {
 			if ( $jsonResult && json_last_error() === JSON_ERROR_NONE ) {
 				if ( $this->isValidMathML( $jsonResult->result ) ) {
 					$this->setMathml( $jsonResult->result );
+					// Avoid PHP 7.1 warning from passing $this by reference
+					$renderer = $this;
 					Hooks::run( 'MathRenderingResultRetrieved',
-						[ &$this, &$jsonResult ] );// Enables debugging of server results
+						[ &$renderer, &$jsonResult ] );// Enables debugging of server results
 					return true;
 				} else {
 					// Do not print bad mathml. It's probably too verbose and might
diff --git a/MathMathML.php b/MathMathML.php
index d29210a..e1e6f06 100644
--- a/MathMathML.php
+++ b/MathMathML.php
@@ -521,8 +521,10 @@ class MathMathML extends MathRenderer {
 			if ( $this->getMode() != 'latexml' && $this->inputType != 'pmml' ) {
 				$this->setMathml( $jsonResult->mml );
 			}
+			// Avoid PHP 7.1 warning from passing $this by reference
+			$renderer = $this;
 			Hooks::run( 'MathRenderingResultRetrieved',
-				[ &$this, &$jsonResult ] ); // Enables debugging of server results
+				[ &$renderer, &$jsonResult ] ); // Enables debugging of server results
 			return true;
 		} else {
 			$this->lastError = $this->getError( 'math_unknown_error', $host );
diff --git a/MathTexvc.php b/MathTexvc.php
index 7e130f9..88c8610 100644
--- a/MathTexvc.php
+++ b/MathTexvc.php
@@ -275,7 +275,9 @@ class MathTexvc extends MathRenderer {
 			$this->setHash( $newHash );
 		}
 
-		Hooks::run( 'MathAfterTexvc', [ &$this, &$errmsg ] );
+		// Avoid PHP 7.1 warning from passing $this by reference
+		$renderer = $this;
+		Hooks::run( 'MathAfterTexvc', [ &$renderer, &$errmsg ] );
 
 		if ( $errmsg ) {
 			return $errmsg;