diff --git a/libmamba/data/mamba_completion.posix b/libmamba/data/mamba_completion.posix
index b57595801b..9a09d1e015 100644
--- a/libmamba/data/mamba_completion.posix
+++ b/libmamba/data/mamba_completion.posix
@@ -1,5 +1,5 @@
 R"MAMBARAW(
-if [[ -n "$ZSH_VERSION" ]]; then
+if [ -n "${ZSH_VERSION:+x}" ]; then
   autoload -U +X compinit && compinit
   autoload -U +X bashcompinit && bashcompinit
 
@@ -9,7 +9,8 @@ if [[ -n "$ZSH_VERSION" ]]; then
   }
 
   complete -o default -F _umamba_zsh_completions micromamba
-else
+fi
+if [ -n "${BASH_VERSION:+x}" ]; then
   _umamba_bash_completions()
   {
     COMPREPLY=($($MAMBA_EXE completer "${COMP_WORDS[@]:1}"))