diff --git a/zsh/google-cloud.zsh b/zsh/google-cloud.zsh
index b6fa161..c475550 100644
--- a/zsh/google-cloud.zsh
+++ b/zsh/google-cloud.zsh
@@ -6,6 +6,19 @@ if [ -f '/usr/local/Caskroom/google-cloud-sdk/latest/google-cloud-sdk/path.zsh.i
   source '/usr/local/Caskroom/google-cloud-sdk/latest/google-cloud-sdk/path.zsh.inc'
 fi
 
-if [ -f '/usr/local/Caskroom/google-cloud-sdk/latest/google-cloud-sdk/completion.zsh.inc' ]; then
-  source '/usr/local/Caskroom/google-cloud-sdk/latest/google-cloud-sdk/completion.zsh.inc'
+# Lazy load gcloud shell completion on first use.
+if command-exists gcloud; then
+  _python_argcomplete() {
+    load-gcloud-completion
+    _python_argcomplete "$@"
+  }
+
+  compctl -K _python_argcomplete gcloud
+
+  load-gcloud-completion() {
+    unset -f load-gcloud-completion _python_argcomplete
+    if [ -f '/usr/local/Caskroom/google-cloud-sdk/latest/google-cloud-sdk/completion.zsh.inc' ]; then
+      source '/usr/local/Caskroom/google-cloud-sdk/latest/google-cloud-sdk/completion.zsh.inc'
+    fi
+  }
 fi