diff -Naur wp-includes/rewrite.php wp-includes/rewrite.php
--- wp-includes/rewrite.php	2018-12-07 10:16:22.981565000 +0530
+++ wp-includes/rewrite.php	2018-12-07 10:17:27.329405625 +0530
@@ -371,8 +371,10 @@
 	 * for month-slug clashes when `is_month` *or* `is_day`.
 	 */
 	$compare = '';
-	if ( 0 === $postname_index && ( isset( $query_vars['year'] ) || isset( $query_vars['monthnum'] ) ) ) {
+	if ( 0 === $postname_index && isset( $query_vars['year'] ) ) {
 		$compare = 'year';
+	} elseif ( 0 === $postname_index && isset( $query_vars['monthnum'] ) ) {
+		$compare = 'monthnum';
 	} elseif ( '%year%' === $permastructs[ $postname_index - 1 ] && ( isset( $query_vars['monthnum'] ) || isset( $query_vars['day'] ) ) ) {
 		$compare = 'monthnum';
 	} elseif ( '%monthnum%' === $permastructs[ $postname_index - 1 ] && isset( $query_vars['day'] ) ) {