diff --git a/oh-my-zsh.sh b/oh-my-zsh.sh
index 3c0f4f8f5..c217b91bb 100644
--- a/oh-my-zsh.sh
+++ b/oh-my-zsh.sh
@@ -46,7 +46,9 @@ else
 fi
 
 # Save the location of the current completion dump file.
-ZSH_COMPDUMP="${ZDOTDIR:-${HOME}}/.zcompdump-${SHORT_HOST}-${ZSH_VERSION}"
+if [ -z "$ZSH_COMPDUMP" ]; then
+  ZSH_COMPDUMP="${ZDOTDIR:-${HOME}}/.zcompdump-${SHORT_HOST}-${ZSH_VERSION}"
+fi
 
 # Load and run compinit
 autoload -U compinit