diff --git a/wp-includes/version.php b/wp-includes/version.php
index 643d351aed..1b4cf12084 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.2-beta3-31938';
+$wp_version = '4.2-beta3-31939';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.
diff --git a/wp-includes/wp-db.php b/wp-includes/wp-db.php
index ae0ec7ec94..91ad6f2286 100644
--- a/wp-includes/wp-db.php
+++ b/wp-includes/wp-db.php
@@ -2810,7 +2810,16 @@ class wpdb {
 					$client_version = mysql_get_client_info();
 				}
 
-				return version_compare( $client_version, '5.5.3', '>=' );
+				/*
+				 * libmysql has supported utf8mb4 since 5.5.3, same as the MySQL server.
+				 * mysqlnd has supported utf8mb4 since 5.0.9.
+				 */
+				if ( false !== strpos( $client_version, 'mysqlnd' ) ) {
+					$client_version = preg_replace( '/^\D+([\d.]+).*/', '$1', $client_version );
+					return version_compare( $client_version, '5.0.9', '>=' );
+				} else {
+					return version_compare( $client_version, '5.5.3', '>=' );
+				}
 		}
 
 		return false;