diff --git a/README.md b/README.md
index 8331131..72d7a6a 100644
--- a/README.md
+++ b/README.md
@@ -5,11 +5,11 @@ the readings in RRDtool databases, and serves a responsive graph dashboard.
 
 ## What it stores
 
-The service creates `outdoor.rrd`, `wind.rrd`, `bedroom.rrd`, `study.rrd`, and
-`living.rrd`. Each has ten-minute archives for the last two weeks and six-hour
-archives covering a year. Day, two-week, and year PNG graphs are rendered on
-demand. The wind graph splits average wind into 12 colored direction bands and
-draws gusts as a line.
+The service creates `netatmo_outdoor.rrd`, `netatmo_wind.rrd`,
+`netatmo_bedroom.rrd`, `netatmo_study.rrd`, and `netatmo_living.rrd`. Each has
+ten-minute archives for the last two weeks and six-hour archives covering a
+year. Day, two-week, and year PNG graphs are rendered on demand. The wind graph
+splits average wind into 12 colored direction bands and draws gusts as a line.
 
 The Outdoor module does not contain a pressure sensor, so `outdoor.rrd` combines
 its temperature/humidity with pressure from the main station. A module without
diff --git a/netatmo_service/rrd.py b/netatmo_service/rrd.py
index e774234..11c27ef 100644
--- a/netatmo_service/rrd.py
+++ b/netatmo_service/rrd.py
@@ -36,7 +36,7 @@ class RRDStore:
     def path(self, name: str) -> Path:
         if name not in SCHEMAS:
             raise KeyError(name)
-        return self.folder / f"{name}.rrd"
+        return self.folder / f"netatmo_{name}.rrd"
 
     def ensure_all(self) -> None:
         self.folder.mkdir(parents=True, exist_ok=True)
diff --git a/tests/test_rrd.py b/tests/test_rrd.py
new file mode 100644
index 0000000..bb8858e
--- /dev/null
+++ b/tests/test_rrd.py
@@ -0,0 +1,7 @@
+from netatmo_service.rrd import RRDStore
+
+
+def test_rrd_files_have_netatmo_prefix(tmp_path):
+    store = RRDStore(tmp_path)
+    assert store.path("outdoor") == tmp_path / "netatmo_outdoor.rrd"
+    assert store.path("wind") == tmp_path / "netatmo_wind.rrd"