diff --git a/src/nix/get-env.sh b/src/nix/get-env.sh
index 42c806450..a8563c772 100644
--- a/src/nix/get-env.sh
+++ b/src/nix/get-env.sh
@@ -8,6 +8,8 @@ if [[ -n $stdenv ]]; then
     source $stdenv/setup
 fi

+unset -f isMachO
+
 # Better to use compgen, but stdenv bash doesn't have it.
 __vars="$(declare -p)"
 __functions="$(declare -F)"