diff --git a/src/wp-includes/class-wp-list-util.php b/src/wp-includes/class-wp-list-util.php
index 3648cd89f5..c394f2c613 100644
--- a/src/wp-includes/class-wp-list-util.php
+++ b/src/wp-includes/class-wp-list-util.php
@@ -166,8 +166,14 @@ class WP_List_Util {
 			foreach ( $this->output as $key => $value ) {
 				if ( is_object( $value ) ) {
 					$newlist[ $key ] = $value->$field;
-				} else {
+				} elseif ( is_array( $value ) ) {
 					$newlist[ $key ] = $value[ $field ];
+				} else {
+					_doing_it_wrong(
+						__METHOD__,
+						__( 'Values for the input array must be either objects or arrays.' ),
+						'6.2.0'
+					);
 				}
 			}
 
@@ -187,12 +193,18 @@ class WP_List_Util {
 				} else {
 					$newlist[] = $value->$field;
 				}
-			} else {
+			} elseif ( is_array( $value ) ) {
 				if ( isset( $value[ $index_key ] ) ) {
 					$newlist[ $value[ $index_key ] ] = $value[ $field ];
 				} else {
 					$newlist[] = $value[ $field ];
 				}
+			} else {
+				_doing_it_wrong(
+					__METHOD__,
+					__( 'Values for the input array must be either objects or arrays.' ),
+					'6.2.0'
+				);
 			}
 		}
 
diff --git a/tests/phpunit/tests/functions/wpListUtil.php b/tests/phpunit/tests/functions/wpListUtil.php
index f455c94936..f40771681e 100644
--- a/tests/phpunit/tests/functions/wpListUtil.php
+++ b/tests/phpunit/tests/functions/wpListUtil.php
@@ -85,7 +85,7 @@ class Tests_Functions_wpListUtil extends WP_UnitTestCase {
 	}
 
 	/**
-	 * Data provider for test_wp_list_util_pluck_simple().
+	 * Data provider for test_wp_list_util_pluck().
 	 *
 	 * @return array[]
 	 */
@@ -108,6 +108,65 @@ class Tests_Functions_wpListUtil extends WP_UnitTestCase {
 		);
 	}
 
+	/**
+	 * Tests that wp_list_pluck() throws _doing_it_wrong() with invalid input.
+	 *
+	 * @ticket 56650
+	 *
+	 * @dataProvider data_wp_list_pluck_should_throw_doing_it_wrong_with_invalid_input
+	 *
+	 * @covers WP_List_Util::pluck
+	 * @covers ::wp_list_pluck
+	 *
+	 * @expectedIncorrectUsage WP_List_Util::pluck
+	 *
+	 * @param array $input An invalid input array.
+	 */
+	public function test_wp_list_pluck_should_throw_doing_it_wrong_with_invalid_input( $input ) {
+		$this->assertSame( array(), wp_list_pluck( $input, 'a_field' ) );
+	}
+
+	/**
+	 * Tests that wp_list_pluck() throws _doing_it_wrong() with an index key and invalid input.
+	 *
+	 * @ticket 56650
+	 *
+	 * @dataProvider data_wp_list_pluck_should_throw_doing_it_wrong_with_invalid_input
+	 *
+	 * @covers WP_List_Util::pluck
+	 * @covers ::wp_list_pluck
+	 *
+	 * @expectedIncorrectUsage WP_List_Util::pluck
+	 *
+	 * @param array $input An invalid input array.
+	 */
+	public function test_wp_list_pluck_should_throw_doing_it_wrong_with_index_key_and_invalid_input( $input ) {
+		$this->assertSame( array(), wp_list_pluck( $input, 'a_field', 'an_index_key' ) );
+	}
+
+	/**
+	 * Data provider that provides invalid input arrays.
+	 *
+	 * @return array
+	 */
+	public function data_wp_list_pluck_should_throw_doing_it_wrong_with_invalid_input() {
+		return array(
+			'int[] 0'                   => array( array( 0 ) ),
+			'int[] 1'                   => array( array( 1 ) ),
+			'int[] -1'                  => array( array( -1 ) ),
+			'float[] 0.0'               => array( array( 0.0 ) ),
+			'float[] 1.0'               => array( array( 1.0 ) ),
+			'float[] -1.0'              => array( array( -1.0 ) ),
+			'string[] and empty string' => array( array( '' ) ),
+			'string[] and "0"'          => array( array( '0' ) ),
+			'string[] and "1"'          => array( array( '1' ) ),
+			'string[] and "-1"'         => array( array( '-1' ) ),
+			'array and null'            => array( array( null ) ),
+			'array and false'           => array( array( false ) ),
+			'array and true'            => array( array( true ) ),
+		);
+	}
+
 	/**
 	 * @ticket 55300
 	 *