diff --git a/src/WikiTexVC/Nodes/DQ.php b/src/WikiTexVC/Nodes/DQ.php
index 7ee3f1e5a..ddbaab80d 100644
--- a/src/WikiTexVC/Nodes/DQ.php
+++ b/src/WikiTexVC/Nodes/DQ.php
@@ -8,6 +8,7 @@ use MediaWiki\Extension\Math\WikiTexVC\MMLmappings\BaseParsing;
 use MediaWiki\Extension\Math\WikiTexVC\MMLnodes\MMLmrow;
 use MediaWiki\Extension\Math\WikiTexVC\MMLnodes\MMLmsub;
 use MediaWiki\Extension\Math\WikiTexVC\MMLnodes\MMLmunder;
+use MediaWiki\Extension\Math\WikiTexVC\TexUtil;
 
 class DQ extends TexNode {
 	/** @var TexNode */
@@ -57,6 +58,12 @@ class DQ extends TexNode {
 				$outer = new MMLmunder();
 			} else {
 				$outer = new MMLmsub();
+				if ( ( $state['styleargs']['displaystle'] ?? 'true' ) === 'true' ) {
+					$tu = TexUtil::getInstance();
+					if ( $this->base instanceof Literal && $tu->operator( trim( $this->base->getArg() ) ) ) {
+						$outer = new MMLmunder();
+					}
+				}
 			}
 			// Otherwise use default fallback
 			$mmlMrow = new MMLmrow();
diff --git a/src/WikiTexVC/TexUtil.php b/src/WikiTexVC/TexUtil.php
index 114e26289..f859734e2 100644
--- a/src/WikiTexVC/TexUtil.php
+++ b/src/WikiTexVC/TexUtil.php
@@ -6,6 +6,12 @@ namespace MediaWiki\Extension\Math\WikiTexVC;
 
 use InvalidArgumentException;
 
+/**
+ * @method is_literal(string $litArg)
+ * @method latex_function_names(string $getArg)
+ * @method nullary_macro(string $litArg)
+ * @method operator(string $getArg)
+ */
 class TexUtil {
 	/** @var self|null */
 	private static $instance = null;
diff --git a/src/WikiTexVC/texutil.json b/src/WikiTexVC/texutil.json
index 6ab4d718d..068060a90 100644
--- a/src/WikiTexVC/texutil.json
+++ b/src/WikiTexVC/texutil.json
@@ -476,13 +476,16 @@
 		"big_literals": true
 	},
 	"\\bigcap": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\bigcirc": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\bigcup": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\bigg": {
 		"big_literals": true
@@ -497,38 +500,48 @@
 		"big_literals": true
 	},
 	"\\bigodot": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\bigoplus": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\bigotimes": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\bigr": {
 		"big_literals": true
 	},
 	"\\bigsqcup": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\bigstar": {
 		"ams_required": true,
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\bigtriangledown": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\bigtriangleup": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\biguplus": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\bigvee": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\bigwedge": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\binom": {
 		"ams_required": true,
@@ -725,7 +738,8 @@
 		"teubner_required": true
 	},
 	"\\coprod": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\cos": {
 		"latex_function_names": true
@@ -1144,15 +1158,18 @@
 	},
 	"\\iiiint": {
 		"ams_required": true,
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\iiint": {
 		"ams_required": true,
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\iint": {
 		"ams_required": true,
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\image": {
 		"nullary_macro_aliase": "\\Im"
@@ -1182,14 +1199,17 @@
 		"nullary_macro": true
 	},
 	"\\int": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\intBar": {
 		"nullary_macro": true,
+		"operator": true,
 		"stix_required": true
 	},
 	"\\intbar": {
 		"nullary_macro": true,
+		"operator": true,
 		"stix_required": true
 	},
 	"\\intent": {
@@ -1199,7 +1219,8 @@
 	"\\intercal": {
 		"ams_required": true,
 		"is_literal": true,
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\iota": {
 		"is_literal": true,
@@ -1946,7 +1967,8 @@
 		"nullary_macro": true
 	},
 	"\\prod": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\projlim": {
 		"ams_required": true,
@@ -2248,7 +2270,8 @@
 		"nullary_macro": true
 	},
 	"\\sum": {
-		"nullary_macro": true
+		"nullary_macro": true,
+		"operator": true
 	},
 	"\\sup": {
 		"latex_function_names": true
diff --git a/tests/phpunit/unit/WikiTexVC/Nodes/DQTest.php b/tests/phpunit/unit/WikiTexVC/Nodes/DQTest.php
index e2a4c4bd8..3d85df2bd 100644
--- a/tests/phpunit/unit/WikiTexVC/Nodes/DQTest.php
+++ b/tests/phpunit/unit/WikiTexVC/Nodes/DQTest.php
@@ -4,6 +4,8 @@ namespace MediaWiki\Extension\Math\Tests\WikiTexVC\Nodes;
 
 use ArgumentCountError;
 use MediaWiki\Extension\Math\WikiTexVC\MMLnodes\MMLmrow;
+use MediaWiki\Extension\Math\WikiTexVC\MMLnodes\MMLmsub;
+use MediaWiki\Extension\Math\WikiTexVC\MMLnodes\MMLmunder;
 use MediaWiki\Extension\Math\WikiTexVC\Nodes\DQ;
 use MediaWiki\Extension\Math\WikiTexVC\Nodes\Literal;
 use MediaWiki\Extension\Math\WikiTexVC\Nodes\TexArray;
@@ -56,4 +58,16 @@ class DQTest extends MediaWikiUnitTestCase {
 		$this->assertStringContainsString( ( new MMLmrow() )->getEmpty(), $dq->renderMML() );
 	}
 
+	public function testBigSum() {
+		$dq = new DQ( new Literal( '\\sum' ), new Literal( 'i' ) );
+		$this->assertStringContainsString( ( new MMLmunder() )->getStart(), $dq->renderMML() );
+	}
+
+	public function testSmallSum() {
+		$dq = new DQ( new Literal( '\\sum' ), new Literal( 'i' ) );
+		$this->assertStringContainsString(
+			( new MMLmsub() )->getStart(),
+			$dq->renderMML( [], [ 'styleargs' => [ 'displaystle' => 'false' ] ] ) );
+	}
+
 }
diff --git a/tests/phpunit/unit/WikiTexVC/TexUtilTest.php b/tests/phpunit/unit/WikiTexVC/TexUtilTest.php
index 8ba268fd9..a388d6570 100644
--- a/tests/phpunit/unit/WikiTexVC/TexUtilTest.php
+++ b/tests/phpunit/unit/WikiTexVC/TexUtilTest.php
@@ -76,6 +76,7 @@ class TexUtilTest extends MediaWikiUnitTestCase {
 			'mhchem_single_macro',
 			'nullary_macro',
 			'nullary_macro_in_mbox',
+			'operator',
 			'other_delimiters1',
 			'other_delimiters2',
 			'over_operator',