diff --git a/projects/packages/waf/tests/php/unit/test-waf-blocklog-manager.php b/projects/packages/waf/tests/php/unit/test-waf-blocklog-manager.php
index c736d257c35fa..a48c05c4af1a4 100644
--- a/projects/packages/waf/tests/php/unit/test-waf-blocklog-manager.php
+++ b/projects/packages/waf/tests/php/unit/test-waf-blocklog-manager.php
@@ -28,7 +28,7 @@ public function testWriteBlocklog() {
 		$file_content = file_get_contents( $waf_log_path );
 
 		$this->assertTrue( file_exists( $waf_log_path ) );
-		$this->assertStringContainsString( '{"rule_id":"1337","reason":"test block"', $file_content );
+		$this->assertFalse( strpos( $file_content, '{"rule_id":"1337","reason":"test block"' ) === false );
 
 		unlink( $waf_log_path );
 	}