diff --git a/powerlevel9k.zsh-theme b/powerlevel9k.zsh-theme
index 701bd99b..0a73a902 100755
--- a/powerlevel9k.zsh-theme
+++ b/powerlevel9k.zsh-theme
@@ -22,7 +22,7 @@
 
 # Bail out if it's not the first time the file is being sourced.
 # Second sourcing will cause mayhem.
-[[ -v _P9K_SOURCED ]] && return
+[[ -n "${_P9K_SOURCED}" ]] && return
 readonly _P9K_SOURCED=1
 
 typeset -g _P9K_INSTALLATION_DIR