diff --git a/powerlevel9k.zsh-theme b/powerlevel9k.zsh-theme
index 35f3f099..8b1c2513 100755
--- a/powerlevel9k.zsh-theme
+++ b/powerlevel9k.zsh-theme
@@ -126,7 +126,7 @@ typeset -gH _P9K_CACHE_CHANNEL=${$(mktemp -u)%/*}/p9k_cache_channel.$$
 _p9k_cache_set() {
   # Uncomment to see cache misses.
   # echo "cache: ${(qq)1} => ${(qq)2}" >&2
-  echo -E "_p9k_cache_data+=(${(qq)1} ${(qq)2})" >>$_P9K_CACHE_CHANNEL
+  echo -E "_p9k_cache_data+=(${(qq)1} ${(qq)2})" >>!$_P9K_CACHE_CHANNEL
   _P9K_RETVAL=$2
 }