diff --git a/lib/functions.zsh b/lib/functions.zsh
index 63ab755cf..ff538c88d 100644
--- a/lib/functions.zsh
+++ b/lib/functions.zsh
@@ -7,7 +7,7 @@ function uninstall_oh_my_zsh() {
 }
 
 function upgrade_oh_my_zsh() {
-  /usr/bin/env ZSH=$ZSH /bin/sh $ZSH/tools/upgrade.sh
+  /usr/bin/env ZSH=$ZSH /bin/bash $ZSH/tools/upgrade.sh
 }
 
 function take() {