diff --git a/src/wp-includes/query.php b/src/wp-includes/query.php
index 12c532628f..bc205894c6 100644
--- a/src/wp-includes/query.php
+++ b/src/wp-includes/query.php
@@ -1593,7 +1593,7 @@ class WP_Query {
 		$qv['monthnum'] = absint($qv['monthnum']);
 		$qv['day'] = absint($qv['day']);
 		$qv['w'] = absint($qv['w']);
-		$qv['m'] = preg_replace( '|[^0-9]|', '', $qv['m'] );
+		$qv['m'] = is_scalar( $qv['m'] ) ? preg_replace( '|[^0-9]|', '', $qv['m'] ) : '';
 		$qv['paged'] = absint($qv['paged']);
 		$qv['cat'] = preg_replace( '|[^0-9,-]|', '', $qv['cat'] ); // comma separated list of positive or negative integers
 		$qv['author'] = preg_replace( '|[^0-9,-]|', '', $qv['author'] ); // comma separated list of positive or negative integers
diff --git a/tests/phpunit/tests/query/date.php b/tests/phpunit/tests/query/date.php
index 9af9655bdc..ed5231b2c6 100644
--- a/tests/phpunit/tests/query/date.php
+++ b/tests/phpunit/tests/query/date.php
@@ -258,6 +258,18 @@ class Tests_Query_Date extends WP_UnitTestCase {
 		$this->assertEquals( $expected_dates, wp_list_pluck( $posts, 'post_date' ) );
 	}
 
+	/**
+	 * @ticket 36718
+	 */
+	public function test_non_scalar_m_should_be_discarded() {
+		$expected = $this->_get_query_result( );
+		$posts    = $this->_get_query_result( array(
+			'm' => array( '1234' ), // ignored
+		) );
+
+		$this->assertEquals( $expected, $posts );
+	}
+
 	public function test_simple_monthnum_expecting_results() {
 		$posts = $this->_get_query_result( array(
 			'monthnum' => 5,