diff --git a/src/wp-includes/class-wp-date-query.php b/src/wp-includes/class-wp-date-query.php
index 2f7ef7e28c..67afda2701 100644
--- a/src/wp-includes/class-wp-date-query.php
+++ b/src/wp-includes/class-wp-date-query.php
@@ -853,7 +853,7 @@ class WP_Date_Query {
 	 *
 	 * You can pass an array of values (year, month, etc.) with missing parameter values being defaulted to
 	 * either the maximum or minimum values (controlled by the $default_to parameter). Alternatively you can
-	 * pass a string that will be run through strtotime().
+	 * pass a string that will be passed to date_create().
 	 *
 	 * @since 3.7.0
 	 *
@@ -865,8 +865,6 @@ class WP_Date_Query {
 	 * @return string|false A MySQL format date/time or false on failure
 	 */
 	public function build_mysql_datetime( $datetime, $default_to_max = false ) {
-		$now = current_time( 'timestamp' );
-
 		if ( ! is_array( $datetime ) ) {
 
 			/*
@@ -907,15 +905,23 @@ class WP_Date_Query {
 
 			// If no match is found, we don't support default_to_max.
 			if ( ! is_array( $datetime ) ) {
-				// @todo Timezone issues here possibly
-				return gmdate( 'Y-m-d H:i:s', strtotime( $datetime, $now ) );
+				$wp_timezone = wp_timezone();
+
+				// Assume local timezone if not provided.
+				$dt = date_create( $datetime, $wp_timezone );
+
+				if ( false === $dt ) {
+					return gmdate( 'Y-m-d H:i:s', false );
+				}
+
+				return $dt->setTimezone( $wp_timezone )->format( 'Y-m-d H:i:s' );
 			}
 		}
 
 		$datetime = array_map( 'absint', $datetime );
 
 		if ( ! isset( $datetime['year'] ) ) {
-			$datetime['year'] = gmdate( 'Y', $now );
+			$datetime['year'] = current_time( 'Y' );
 		}
 
 		if ( ! isset( $datetime['month'] ) ) {
diff --git a/tests/phpunit/tests/date/query.php b/tests/phpunit/tests/date/query.php
index 18c2c95218..acf4e5bf7d 100644
--- a/tests/phpunit/tests/date/query.php
+++ b/tests/phpunit/tests/date/query.php
@@ -509,40 +509,81 @@ class Tests_WP_Date_Query extends WP_UnitTestCase {
 		$this->assertSame( $expected, $found );
 	}
 
-	public function test_build_mysql_datetime_default_to_max_true() {
+	/**
+	 * @ticket 41782
+	 *
+	 * @dataProvider mysql_datetime_input_provider
+	 *
+	 * @param array|string $datetime       Array or string date input.
+	 * @param string       $expected       Expected built result.
+	 * @param bool         $default_to_max Flag to default missing values to max.
+	 */
+	public function test_build_mysql_datetime( $datetime, $expected, $default_to_max = false ) {
 		$q = new WP_Date_Query( array() );
 
-		$found = $q->build_mysql_datetime(
-			array(
-				'year' => 2011,
-			),
-			true
-		);
-		$this->assertSame( '2011-12-31 23:59:59', $found );
+		$found = $q->build_mysql_datetime( $datetime, $default_to_max );
+
+		$message = "Expected {$expected}, got {$found}";
+		$this->assertEquals( strtotime( $expected ), strtotime( $found ), $message, 10 );
 	}
 
-	public function test_build_mysql_datetime_default_to_max_false() {
-		$q = new WP_Date_Query( array() );
-
-		$found = $q->build_mysql_datetime(
-			array(
-				'year' => 2011,
-			),
-			false
+	public function mysql_datetime_input_provider() {
+		return array(
+			array( '2019-06-04T08:18:24+03:00', '2019-06-04 05:18:24' ),
+			array( '2019-06-04T05:18:24+00:00', '2019-06-04 05:18:24' ),
+			array( array(), current_time( 'Y' ) . '-01-01 00:00:00' ),
+			array( array( 'year' => 2011 ), '2011-12-31 23:59:59', true ),
+			array( array( 'year' => 2011 ), '2011-01-01 00:00:00' ),
+			array( '2011', '2011-01-01 00:00:00' ),
+			array( '2011-02', '2011-02-01 00:00:00' ),
+			array( '2011-02-03', '2011-02-03 00:00:00' ),
+			array( '2011-02-03 13:30', '2011-02-03 13:30:00' ),
+			array( '2011-02-03 13:30:35', '2011-02-03 13:30:35' ),
 		);
-		$this->assertSame( '2011-01-01 00:00:00', $found );
 	}
 
-	public function test_build_mysql_datetime_default_to_max_default_to_false() {
+	/**
+	 * @ticket 41782
+	 *
+	 * @dataProvider mysql_datetime_input_provider_custom_timezone
+	 *
+	 * @param array|string $datetime       Array or string date input.
+	 * @param string       $expected       Expected built result.
+	 * @param bool         $default_to_max Flag to default missing values to max.
+	 */
+	public function test_build_mysql_datetime_with_custom_timezone( $datetime, $expected, $default_to_max = false ) {
+		update_option( 'timezone_string', 'Europe/Kiev' );
+
 		$q = new WP_Date_Query( array() );
 
-		$found = $q->build_mysql_datetime(
-			array(
-				'year' => 2011,
-			),
-			false
+		$found = $q->build_mysql_datetime( $datetime, $default_to_max );
+
+		$message = "Expected {$expected}, got {$found}";
+		$this->assertEquals( strtotime( $expected ), strtotime( $found ), $message, 10 );
+
+	}
+
+	public function mysql_datetime_input_provider_custom_timezone() {
+		return array(
+			array( '2019-06-04T08:18:24+03:00', '2019-06-04 08:18:24' ),
+			array( '2019-06-04T05:18:24+00:00', '2019-06-04 08:18:24' ),
 		);
-		$this->assertSame( '2011-01-01 00:00:00', $found );
+	}
+
+	/**
+	 * @ticket 41782
+	 */
+	public function test_build_mysql_datetime_with_relative_date() {
+		update_option( 'timezone_string', 'Europe/Kiev' );
+
+		$q = new WP_Date_Query( array() );
+
+		$yesterday = new DateTimeImmutable( '-1 day', wp_timezone() );
+		$expected  = $yesterday->format( 'Y-m-d H:i:s' );
+		$found     = $q->build_mysql_datetime( '-1 day' );
+
+		$message = "Expected {$expected}, got {$found}";
+		$this->assertEquals( strtotime( $expected ), strtotime( $found ), $message, 10 );
 	}
 
 	public function test_build_time_query_insufficient_time_values() {