diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index 06f9b9065e..4904cd9e7e 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -39,7 +39,7 @@ When you introduce new `public` sniff properties, or your sniff extends a class
 
 ## Pre-requisites
 * WordPress-Coding-Standards
-* PHP_CodeSniffer 3.8.0 or higher
+* PHP_CodeSniffer 3.9.0 or higher
 * PHPCSUtils 1.0.9 or higher
 * PHPCSExtra 1.2.1 or higher
 * PHPUnit 4.x - 9.x
diff --git a/Tests/RulesetCheck/class-ruleset-test.inc b/Tests/RulesetCheck/class-ruleset-test.inc
index b674946ded..e45a2bc7d6 100644
--- a/Tests/RulesetCheck/class-ruleset-test.inc
+++ b/Tests/RulesetCheck/class-ruleset-test.inc
@@ -64,7 +64,7 @@ class Ruleset_Test {
 			if ( preg_match( '`' . preg_quote( $param_a, '`' ) . '`i', $param_b ) === 1 ) {
 				echo esc_html( "doublequoted $string" );
 			} elseif ( $this->a ) {
-				$ab = $a % $b + $c / $d && $param_a || $param_b >> $bitshift;
+				$ab = $a % $b + $c / $d && ( $param_a || $param_b >> $bitshift );
 			}
 		};
 
diff --git a/WordPress-Extra/ruleset.xml b/WordPress-Extra/ruleset.xml
index 8b065c7a1f..ab0e8db3b7 100644
--- a/WordPress-Extra/ruleset.xml
+++ b/WordPress-Extra/ruleset.xml
@@ -41,6 +41,10 @@
 		 https://github.com/WordPress/WordPress-Coding-Standards/pull/809 -->
 	<rule ref="Squiz.PHP.DisallowSizeFunctionsInLoops"/>
 
+	<!-- Do not allow ambiguous conditions.
+		 https://github.com/WordPress/WordPress-Coding-Standards/issues/2429 -->
+	<rule ref="Generic.CodeAnalysis.RequireExplicitBooleanOperatorPrecedence"/>
+
 	<!-- Check that functions use all parameters passed.
 		 https://github.com/WordPress/WordPress-Coding-Standards/issues/1510 -->
 	<rule ref="Generic.CodeAnalysis.UnusedFunctionParameter">
diff --git a/composer.json b/composer.json
index f54f513325..2a41cd4c51 100644
--- a/composer.json
+++ b/composer.json
@@ -21,7 +21,7 @@
 		"ext-libxml": "*",
 		"ext-tokenizer": "*",
 		"ext-xmlreader": "*",
-		"squizlabs/php_codesniffer": "^3.8.0",
+		"squizlabs/php_codesniffer": "^3.9.0",
 		"phpcsstandards/phpcsutils": "^1.0.9",
 		"phpcsstandards/phpcsextra": "^1.2.1"
 	},