diff --git a/tests/test_functions/isolated-tmux-start.fish b/tests/test_functions/isolated-tmux-start.fish
index 984ef321b..0a4f75d5f 100644
--- a/tests/test_functions/isolated-tmux-start.fish
+++ b/tests/test_functions/isolated-tmux-start.fish
@@ -49,6 +49,7 @@ function isolated-tmux-start --wraps fish
         set fish_history ""
         # No transient prompt.
         set fish_transient_prompt 0
+        set -g CDPATH
     ' $argv
     # Set the correct permissions for the newly created socket to allow future connections.
     # This is required at least under WSL or else each invocation will return a permissions error.