diff --git a/homeassistant/components/derivative/strings.json b/homeassistant/components/derivative/strings.json
index bfdf861a019..f1b7375ae07 100644
--- a/homeassistant/components/derivative/strings.json
+++ b/homeassistant/components/derivative/strings.json
@@ -15,7 +15,7 @@
         },
         "data_description": {
           "round": "Controls the number of decimal digits in the output.",
-          "time_window": "If set, the sensor's value is a time weighted moving average of derivatives within this window.",
+          "time_window": "If set, the sensor's value is a time-weighted moving average of derivatives within this window.",
           "unit_prefix": "The output will be scaled according to the selected metric prefix and time unit of the derivative."
         }
       }