diff --git a/tests/phpunit/includes/functions.php b/tests/phpunit/includes/functions.php
index 17e075c701..27b12b5b18 100644
--- a/tests/phpunit/includes/functions.php
+++ b/tests/phpunit/includes/functions.php
@@ -94,7 +94,7 @@ function _test_filter_build_unique_id( $tag, $function, $priority ) {
 		return spl_object_hash( $function[0] ) . $function[1];
 	} elseif ( is_string( $function[0] ) ) {
 		// Static calling.
-		return $function[0] . $function[1];
+		return $function[0] . '::' . $function[1];
 	}
 }