diff --git a/includes/EditPage.php b/includes/EditPage.php
index 79af9d4f970..fcd7d130799 100644
--- a/includes/EditPage.php
+++ b/includes/EditPage.php
@@ -2055,21 +2055,14 @@ ERROR;
 		);
 
 		// SpamRegexConstraint: ensure that the summary and text don't match the spam regex
-		if ( $this->section == 'new' ) {
-			// $wgSpamRegex is enforced on this new heading/summary because, unlike
-			// regular summaries, it is added to the actual wikitext.
-			// sectiontitle is only set if the API is used with `sectiontitle`, otherwise
-			// the summary is used which comes from the API `summary` parameter or the
-			// "Add Topic" user interface
-			$sectionHeadingToCheck = ( $this->sectiontitle !== '' ? $this->sectiontitle : $this->summary );
-		} else {
-			// No section heading to check
-			$sectionHeadingToCheck = '';
-		}
+		// FIXME $this->section is documented to always be a string, but it can be null
+		// since importFormData does not provide a default when getting the section from
+		// WebRequest, and the default default is null.
 		$constraintRunner->addConstraint(
 			$constraintFactory->newSpamRegexConstraint(
 				$this->summary,
-				$sectionHeadingToCheck,
+				$this->section === null ? '' : $this->section,
+				$this->sectiontitle,
 				$this->textbox1,
 				$this->context->getRequest()->getIP(),
 				$this->mTitle
@@ -2197,7 +2190,6 @@ ERROR;
 
 			$result['sectionanchor'] = '';
 			if ( $this->section == 'new' ) {
-				// @phan-suppress-next-line PhanSuspiciousValueComparison
 				if ( $this->sectiontitle !== '' ) {
 					// Insert the section title above the content.
 					$content = $content->addSectionHeader( $this->sectiontitle );
@@ -2260,7 +2252,6 @@ ERROR;
 			}
 
 			// If sectiontitle is set, use it, otherwise use the summary as the section title.
-			// @phan-suppress-next-line PhanSuspiciousValueComparison
 			if ( $this->sectiontitle !== '' ) {
 				$sectionTitle = $this->sectiontitle;
 			} else {
diff --git a/includes/editpage/Constraint/EditConstraintFactory.php b/includes/editpage/Constraint/EditConstraintFactory.php
index e11f42ccd23..26b29c6a808 100644
--- a/includes/editpage/Constraint/EditConstraintFactory.php
+++ b/includes/editpage/Constraint/EditConstraintFactory.php
@@ -210,6 +210,7 @@ class EditConstraintFactory {
 
 	/**
 	 * @param string $summary
+	 * @param string $section
 	 * @param string $sectionHeading
 	 * @param string $text
 	 * @param string $reqIP
@@ -218,6 +219,7 @@ class EditConstraintFactory {
 	 */
 	public function newSpamRegexConstraint(
 		string $summary,
+		string $section,
 		string $sectionHeading,
 		string $text,
 		string $reqIP,
@@ -227,6 +229,7 @@ class EditConstraintFactory {
 			$this->loggerFactory->getLogger( 'SpamRegex' ),
 			$this->spamRegexChecker,
 			$summary,
+			$section,
 			$sectionHeading,
 			$text,
 			$reqIP,
diff --git a/includes/editpage/Constraint/SpamRegexConstraint.php b/includes/editpage/Constraint/SpamRegexConstraint.php
index 3043a4383f7..f2467ec40dc 100644
--- a/includes/editpage/Constraint/SpamRegexConstraint.php
+++ b/includes/editpage/Constraint/SpamRegexConstraint.php
@@ -62,6 +62,7 @@ class SpamRegexConstraint implements IEditConstraint {
 	 * @param LoggerInterface $logger for logging hits
 	 * @param SpamChecker $spamChecker
 	 * @param string $summary
+	 * @param string $section
 	 * @param string $sectionHeading
 	 * @param string $text
 	 * @param string $reqIP for logging hits
@@ -71,15 +72,28 @@ class SpamRegexConstraint implements IEditConstraint {
 		LoggerInterface $logger,
 		SpamChecker $spamChecker,
 		string $summary,
+		string $section,
 		string $sectionHeading,
 		string $text,
 		string $reqIP,
 		Title $title
 	) {
+		if ( $section == 'new' ) {
+			// $wgSpamRegex is enforced on this new heading/summary because, unlike
+			// regular summaries, it is added to the actual wikitext.
+			// sectiontitle is only set if the API is used with `sectiontitle`, otherwise
+			// the summary is used which comes from the API `summary` parameter or the
+			// "Add Topic" user interface
+			$sectionHeadingToCheck = ( $sectionHeading !== '' ? $sectionHeading : $summary );
+		} else {
+			// No section heading to check
+			$sectionHeadingToCheck = '';
+		}
+
 		$this->logger = $logger;
 		$this->spamChecker = $spamChecker;
 		$this->summary = $summary;
-		$this->sectionHeading = $sectionHeading;
+		$this->sectionHeading = $sectionHeadingToCheck;
 		$this->text = $text;
 		$this->reqIP = $reqIP;
 		$this->title = $title;
diff --git a/tests/phpunit/unit/includes/editpage/Constraint/SpamRegexConstraintTest.php b/tests/phpunit/unit/includes/editpage/Constraint/SpamRegexConstraintTest.php
index 2a1d66908bc..589f64b35f0 100644
--- a/tests/phpunit/unit/includes/editpage/Constraint/SpamRegexConstraintTest.php
+++ b/tests/phpunit/unit/includes/editpage/Constraint/SpamRegexConstraintTest.php
@@ -62,6 +62,7 @@ class SpamRegexConstraintTest extends MediaWikiUnitTestCase {
 			$logger,
 			$spamChecker,
 			$summary,
+			'new',
 			$sectionHeading,
 			$text,
 			'Request-IP',
@@ -94,6 +95,7 @@ class SpamRegexConstraintTest extends MediaWikiUnitTestCase {
 			$logger,
 			$spamChecker,
 			$summary,
+			'new',
 			$sectionHeading,
 			$text,
 			'Request-IP',