diff --git a/src/pyopensky/config.py b/src/pyopensky/config.py
index 6cbe0c7..7753061 100644
--- a/src/pyopensky/config.py
+++ b/src/pyopensky/config.py
@@ -98,6 +98,7 @@ class Resolution(TypedDict, total=False):
 NAME_RESOLUTION: dict[str, Resolution] = {
     # Cache configuration
     "cache_dir": dict(
+        environment_variable="OPENSKY_CACHE",
         opensky_category="cache",
         opensky_name="path",
         traffic_category="cache",