diff --git a/README.md b/README.md
index 1904e49..27ba47e 100644
--- a/README.md
+++ b/README.md
@@ -130,7 +130,7 @@ The following parameters must be set (mandatory) for the container to function:
 |----------------------|---------|---------|
 | `LAT` or `READSB_LAT` | The latitude of your antenna | |
 | `LONG` or `READSB_LON` | The longitude of your antenna | |
-| `ALT` or `READSB_ALT` | The altitude of your antenna over ground level. For example, `15m` or `45ft` | |
+| `ALT` or `READSB_ALT` | The altitude of your antenna above sea level. For example, `15m` or `45ft` | |
 | `TZ` | Your local timezone in [TZ-database-name](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones) format | |
 
 ##### Optional Parameters