diff --git a/src/MathRenderer.php b/src/MathRenderer.php
index 6eeb943..13f6042 100644
--- a/src/MathRenderer.php
+++ b/src/MathRenderer.php
@@ -214,7 +214,7 @@ abstract class MathRenderer {
 		$mf = wfMessage( 'math_failure' )->inContentLanguage()->escaped();
 		$errmsg = wfMessage( $msg, $parameters )->inContentLanguage()->escaped();
 		$source = htmlspecialchars( str_replace( "\n", ' ', $this->tex ) );
-		return "<strong class='error texerror'>$mf ($errmsg): $source</strong>\n";
+		return "<strong class=\"error texerror\">$mf ($errmsg): $source</strong>\n";
 	}
 
 	/**
diff --git a/tests/ParserTest.json b/tests/ParserTest.json
index fb45656..a37eaac 100644
--- a/tests/ParserTest.json
+++ b/tests/ParserTest.json
@@ -2123,7 +2123,7 @@
     {
         "input": " with a thumbnail- we don't render math in the parsertests by default, so math is not stripped and turns up as escaped &lt;math&gt; tags. [[Image:foobar.jpg|thumb|<math>2+2",
         "params": [],
-        "output": "<strong class='error texerror'>Failed to parse (syntax error): {\\displaystyle  with a thumbnail- we don't render math in the parsertests by default, so math is not stripped and turns up as escaped &amp;lt;math&amp;gt; tags. [[Image:foobar.jpg|thumb|&lt;math&gt;2+2}<\/strong>\n"
+        "output": "<strong class=\"error texerror\">Failed to parse (syntax error): {\\displaystyle  with a thumbnail- we don't render math in the parsertests by default, so math is not stripped and turns up as escaped &amp;lt;math&amp;gt; tags. [[Image:foobar.jpg|thumb|&lt;math&gt;2+2}<\/strong>\n"
     },
     {
         "input": " with a thumbnail- math enabled [[Image:foobar.jpg|thumb|<math>2+2",
@@ -2293,12 +2293,12 @@
     {
         "input": "",
         "params": [],
-        "output": "<strong class='error texerror'>Failed to parse (Conversion error. Server (&quot;https:\/\/wikimedia.org\/api\/rest_&quot;) reported: &quot;Cannot get mml. Expected width &gt; 0.&quot;): {\\displaystyle }<\/strong>\n"
+        "output": "<strong class=\"error texerror\">Failed to parse (Conversion error. Server (&quot;https:\/\/wikimedia.org\/api\/rest_&quot;) reported: &quot;Cannot get mml. Expected width &gt; 0.&quot;): {\\displaystyle }<\/strong>\n"
     },
     {
         "input": " ",
         "params": [],
-        "output": "<strong class='error texerror'>Failed to parse (Conversion error. Server (&quot;https:\/\/wikimedia.org\/api\/rest_&quot;) reported: &quot;Cannot get mml. Expected width &gt; 0.&quot;): {\\displaystyle  }<\/strong>\n"
+        "output": "<strong class=\"error texerror\">Failed to parse (Conversion error. Server (&quot;https:\/\/wikimedia.org\/api\/rest_&quot;) reported: &quot;Cannot get mml. Expected width &gt; 0.&quot;): {\\displaystyle  }<\/strong>\n"
     },
     {
         "input": "\\left(\\begin{smallmatrix}a & b\\\\ c & d\\end{smallmatrix}\\right)",
@@ -2310,4 +2310,4 @@
         "params": [],
         "output": "<img src=\"085412b37ef2ac62058f72715866515b3ee71f39\" class=\"mwe-math-fallback-image-inline\" aria-hidden=\"true\" style=\"vertical-align: -1.171ex; width:1.417ex; height:3.343ex;\" alt=\"{\\displaystyle \\AA}\"\/>"
     }
-]
\ No newline at end of file
+]