diff --git a/pytec/pytec/gui/view/param_tree.json b/pytec/pytec/gui/view/param_tree.json
index 766180d..595ab47 100644
--- a/pytec/pytec/gui/view/param_tree.json
+++ b/pytec/pytec/gui/view/param_tree.json
@@ -290,7 +290,7 @@
                "title": "Ki",
                "type": "float",
                "step": 0.1,
-               "suffix": "Hz",
+               "suffix": "τ⁻¹",
                "noUnitEditing": true,
                "compactHeight": false,
                "thermostat:set_param": {
@@ -305,7 +305,7 @@
                "title": "Kd",
                "type": "float",
                "step": 0.1,
-               "suffix": "s",
+               "suffix": "τ",
                "noUnitEditing": true,
                "compactHeight": false,
                "thermostat:set_param": {