diff --git a/pytec/pytec/gui/view/param_tree.json b/pytec/pytec/gui/view/param_tree.json
index 4787d54..ee230fc 100644
--- a/pytec/pytec/gui/view/param_tree.json
+++ b/pytec/pytec/gui/view/param_tree.json
@@ -303,7 +303,7 @@
                "title": "Ki",
                "type": "float",
                "step": 0.1,
-               "suffix": "Hz",
+               "suffix": "τ⁻¹",
                "noUnitEditing": true,
                "compactHeight": false,
                "thermostat:set_param": {
@@ -318,7 +318,7 @@
                "title": "Kd",
                "type": "float",
                "step": 0.1,
-               "suffix": "s",
+               "suffix": "τ",
                "noUnitEditing": true,
                "compactHeight": false,
                "thermostat:set_param": {