diff --git a/plugins/bundler/README.md b/plugins/bundler/README.md
index 8280a344c..736e74d04 100644
--- a/plugins/bundler/README.md
+++ b/plugins/bundler/README.md
@@ -22,7 +22,7 @@ plugins=(... bundler)
 | `bo`   | `bundle open`     | Opens the source directory for a gem in your bundle      |
 | `bout` | `bundle outdated` | List installed gems with newer versions available        |
 | `bp`   | `bundle package`  | Package your needed .gem files into your application     |
-| `bu`   | `bundle update --all` | Update your gems to the latest available versions    |
+| `bu`   | `bundle update --all` (no arguments) or `bundle update <args>` | Update all gems, or only the given gems/options (e.g. `bu rake`, `bu --ruby`) |
 
 ## Gem wrapper
 
diff --git a/plugins/bundler/bundler.plugin.zsh b/plugins/bundler/bundler.plugin.zsh
index a496d42de..6076be2a9 100644
--- a/plugins/bundler/bundler.plugin.zsh
+++ b/plugins/bundler/bundler.plugin.zsh
@@ -9,7 +9,16 @@ alias bl="bundle list"
 alias bo="bundle open"
 alias bout="bundle outdated"
 alias bp="bundle package"
-alias bu="bundle update --all"
+unalias bu 2>/dev/null
+# `bundle update` needs --all to update everything, but rejects --all when
+# gems or options are given (e.g. `bu <gem>`, `bu --ruby`)
+bu() {
+  if [[ $# -eq 0 ]]; then
+    bundle update --all
+  else
+    bundle update "$@"
+  fi
+}
 
 ## Gem wrapper