diff --git a/zsh/completion.zsh b/zsh/completion.zsh
index 91e87f6..2f38e37 100644
--- a/zsh/completion.zsh
+++ b/zsh/completion.zsh
@@ -51,7 +51,9 @@ zstyle ':completion:::::' completer \
 #TODO: keep _prefix or not?
 
 # ignore case when trying to match typed characters
-zstyle ':completion:*:(^approximate):*' matcher-list 'm:{a-zA-Z-_}={A-Za-z_-}'
+zstyle ':completion:*:(^approximate):*' matcher-list 'm:{[:lower:]}={[:upper:]}' \
+	'+m:{[:upper:]}={[:lower:]}' \
+	'+m:{-_}={_-}'
 
 # allow one mistake per three characters
 zstyle -e ':completion:*:approximate:*' max-errors \