diff --git a/src/wp-includes/class-wp-customize-manager.php b/src/wp-includes/class-wp-customize-manager.php
index 60b07a83f1..761e3216ee 100644
--- a/src/wp-includes/class-wp-customize-manager.php
+++ b/src/wp-includes/class-wp-customize-manager.php
@@ -670,14 +670,15 @@ final class WP_Customize_Manager {
 		if ( ! array_key_exists( $setting->id, $post_values ) ) {
 			return $default;
 		}
-		$value = $setting->sanitize( $post_values[ $setting->id ] );
-		if ( is_null( $value ) || is_wp_error( $value ) ) {
-			return $default;
-		}
+		$value = $post_values[ $setting->id ];
 		$valid = $setting->validate( $value );
 		if ( is_wp_error( $valid ) ) {
 			return $default;
 		}
+		$value = $setting->sanitize( $value );
+		if ( is_null( $value ) || is_wp_error( $value ) ) {
+			return $default;
+		}
 		return $value;
 	}
 
@@ -1007,8 +1008,16 @@ final class WP_Customize_Manager {
 			if ( ! $setting || is_null( $unsanitized_value ) ) {
 				continue;
 			}
-			$validity = $setting->validate( $setting->sanitize( $unsanitized_value ) );
-			if ( false === $validity || null === $validity ) {
+			$validity = $setting->validate( $unsanitized_value );
+			if ( ! is_wp_error( $validity ) ) {
+				$value = $setting->sanitize( $unsanitized_value );
+				if ( is_null( $value ) ) {
+					$validity = false;
+				} elseif ( is_wp_error( $value ) ) {
+					$validity = $value;
+				}
+			}
+			if ( false === $validity ) {
 				$validity = new WP_Error( 'invalid_value', __( 'Invalid value.' ) );
 			}
 			$validities[ $setting_id ] = $validity;
diff --git a/tests/phpunit/tests/customize/manager.php b/tests/phpunit/tests/customize/manager.php
index 437f4101fc..011bd8de2d 100644
--- a/tests/phpunit/tests/customize/manager.php
+++ b/tests/phpunit/tests/customize/manager.php
@@ -190,6 +190,50 @@ class Tests_WP_Customize_Manager extends WP_UnitTestCase {
 		return $validity;
 	}
 
+	/**
+	 * Test the WP_Customize_Manager::post_value() method to make sure that the validation and sanitization are done in the right order.
+	 *
+	 * @ticket 37247
+	 */
+	function test_post_value_validation_sanitization_order() {
+		$default_value = '0';
+		$setting = $this->manager->add_setting( 'numeric', array(
+			'validate_callback' => array( $this, 'filter_customize_validate_numeric' ),
+			'sanitize_callback' => array( $this, 'filter_customize_sanitize_numeric' ),
+		) );
+		$this->assertEquals( $default_value, $this->manager->post_value( $setting, $default_value ) );
+		$this->assertEquals( $default_value, $setting->post_value( $default_value ) );
+
+		$post_value = '42';
+		$this->manager->set_post_value( 'numeric', $post_value );
+		$this->assertEquals( $post_value, $this->manager->post_value( $setting, $default_value ) );
+		$this->assertEquals( $post_value, $setting->post_value( $default_value ) );
+	}
+
+	/**
+	 * Filter customize_validate callback for a numeric value.
+	 *
+	 * @param mixed $value Value.
+	 * @return string|WP_Error
+	 */
+	function filter_customize_sanitize_numeric( $value ) {
+		return absint( $value );
+	}
+
+	/**
+	 * Filter customize_validate callback for a numeric value.
+	 *
+	 * @param WP_Error $validity Validity.
+	 * @param mixed    $value    Value.
+	 * @return WP_Error
+	 */
+	function filter_customize_validate_numeric( $validity, $value ) {
+		if ( ! is_string( $value ) || ! is_numeric( $value ) ) {
+			$validity->add( 'invalid_value_in_validate', __( 'Invalid value.' ), array( 'source' => 'filter_customize_validate_numeric' ) );
+		}
+		return $validity;
+	}
+
 	/**
 	 * Test WP_Customize_Manager::validate_setting_values().
 	 *
@@ -234,6 +278,23 @@ class Tests_WP_Customize_Manager extends WP_UnitTestCase {
 		$this->assertEquals( array( 'source' => 'filter_customize_validate_foo' ), $error->get_error_data() );
 	}
 
+	/**
+	 * Test the WP_Customize_Manager::validate_setting_values() method to make sure that the validation and sanitization are done in the right order.
+	 *
+	 * @ticket 37247
+	 */
+	function test_validate_setting_values_validation_sanitization_order() {
+		$setting = $this->manager->add_setting( 'numeric', array(
+			'validate_callback' => array( $this, 'filter_customize_validate_numeric' ),
+			'sanitize_callback' => array( $this, 'filter_customize_sanitize_numeric' ),
+		) );
+		$post_value = '42';
+		$this->manager->set_post_value( 'numeric', $post_value );
+		$validities = $this->manager->validate_setting_values( $this->manager->unsanitized_post_values() );
+		$this->assertCount( 1, $validities );
+		$this->assertEquals( array( 'numeric' => true ), $validities );
+	}
+
 	/**
 	 * Test WP_Customize_Manager::prepare_setting_validity_for_js().
 	 *