diff --git a/html-api-debugger/html-api-integration.php b/html-api-debugger/html-api-integration.php
index 7d9584e..c47c595 100644
--- a/html-api-debugger/html-api-integration.php
+++ b/html-api-debugger/html-api-integration.php
@@ -129,7 +129,11 @@ function get_tree( string $html, array $options ): array {
 					$doctype_name              = $doctype->name;
 					$doctype_public_identifier = $doctype->public_identifier;
 					$doctype_system_identifier = $doctype->system_identifier;
-					if ( $doctype->indicated_compatability_mode !== 'quirks' ) {
+					if (
+						( property_exists( $doctype, 'indicated_compatibility_mode' )
+							? $doctype->indicated_compatibility_mode
+							: $doctype->indicated_compatability_mode ) !== 'quirks'
+					) {
 						$compat_mode = 'CSS1Compat';
 					}
 					break;
@@ -234,7 +238,11 @@ function get_tree( string $html, array $options ): array {
 				$doctype_name              = $doctype->name;
 				$doctype_public_identifier = $doctype->public_identifier;
 				$doctype_system_identifier = $doctype->system_identifier;
-				if ( $doctype->indicated_compatability_mode !== 'quirks' ) {
+				if (
+					( property_exists( $doctype, 'indicated_compatibility_mode' )
+						? $doctype->indicated_compatibility_mode
+						: $doctype->indicated_compatability_mode ) !== 'quirks'
+				) {
 					$compat_mode = 'CSS1Compat';
 				}
 
diff --git a/html-api-debugger/readme.txt b/html-api-debugger/readme.txt
index 84d993d..6f4c63a 100644
--- a/html-api-debugger/readme.txt
+++ b/html-api-debugger/readme.txt
@@ -17,6 +17,7 @@ Please file issues and pull requests on the [GitHub repository](https://github.c
 
 = 2.8 =
 * Silence _doing_it_wrong bookmark notices when providing from HTML context.
+* Adjust doctype info to account for typo fix.
 
 = 2.7 =
 * Preserve attribute value line breaks in tree views.