diff --git a/README.md b/README.md
index 6c2a98ec93..3d0dc8b557 100644
--- a/README.md
+++ b/README.md
@@ -82,6 +82,8 @@ WP-CLI version: 0.25.0
 
 You can update WP-CLI with `wp cli update` ([doc](https://wp-cli.org/commands/cli/update/)), or by repeating the installation steps.
 
+If WP-CLI is owned by root or another system user, you'll need to run `sudo wp cli update`.
+
 Want to live life on the edge? Run `wp cli update --nightly` to use the latest nightly build of WP-CLI. The nightly build is more or less stable enough for you to use in your development environment, and always includes the latest and greatest WP-CLI features.
 
 ### Tab completions
diff --git a/php/WP_CLI/Runner.php b/php/WP_CLI/Runner.php
index 34d60cdff1..0700d01ee7 100644
--- a/php/WP_CLI/Runner.php
+++ b/php/WP_CLI/Runner.php
@@ -661,12 +661,18 @@ private function init_config() {
 	}
 
 	private function check_root() {
-		if ( $this->config['allow-root'] )
+		if ( $this->config['allow-root'] ) {
 			return; # they're aware of the risks!
-		if ( !function_exists( 'posix_geteuid') )
+		}
+		if ( count( $this->arguments ) >= 2 && 'cli' === $this->arguments[0] && 'update' === $this->arguments[1] ) {
+			return; # make it easier to update root-owned copies
+		}
+		if ( !function_exists( 'posix_geteuid') ) {
 			return; # posix functions not available
-		if ( posix_geteuid() !== 0 )
+		}
+		if ( posix_geteuid() !== 0 ) {
 			return; # not root
+		}
 
 		WP_CLI::error(
 			"YIKES! It looks like you're running this as root. You probably meant to " .