diff --git a/metrics.py b/metrics.py
index 6c5ccc0..ad9e057 100644
--- a/metrics.py
+++ b/metrics.py
@@ -1,59 +1,74 @@
 import json
 import os
-import threading
-from os.path import basename
+import subprocess
 
-from prometheus_client import Gauge
+from prometheus_client.core import REGISTRY
 from prometheus_client.exposition import start_http_server
+from prometheus_client.metrics_core import GaugeMetricFamily
 
 import rawfile_util
 from rawfile_util import attached_loops
-from util import run_out
-
-VOLUME_ID = "volume_id"
-
-fs_size = Gauge(
-    "rawfile_filesystem_size_bytes", "Filesystem size in bytes.", [VOLUME_ID]
-)
-fs_free = Gauge(
-    "rawfile_filesystem_avail_bytes", "Filesystem free space in bytes", [VOLUME_ID]
-)
-dev_size = Gauge("rawfile_device_size_bytes", "Device size in bytes.", [VOLUME_ID])
-dev_free = Gauge(
-    "rawfile_device_free_bytes", "Device free space in bytes.", [VOLUME_ID]
-)
 
 
-def collect_stats():
-    blockdevices = json.loads(run_out("lsblk --json").stdout.decode())["blockdevices"]
+class VolumeStatsCollector(object):
+    def collect(self):
+        VOLUME_ID = "volume_id"
+        fs_size = GaugeMetricFamily(
+            "rawfile_filesystem_size_bytes",
+            "Filesystem size in bytes.",
+            labels=[VOLUME_ID],
+        )
+        fs_free = GaugeMetricFamily(
+            "rawfile_filesystem_avail_bytes",
+            "Filesystem free space in bytes",
+            labels=[VOLUME_ID],
+        )
+        dev_size = GaugeMetricFamily(
+            "rawfile_device_size_bytes", "Device size in bytes.", labels=[VOLUME_ID]
+        )
+        dev_free = GaugeMetricFamily(
+            "rawfile_device_free_bytes",
+            "Device free space in bytes.",
+            labels=[VOLUME_ID],
+        )
 
-    def dev_to_mountpoint(dev_name):
-        dev_name = basename(dev_name)
-        matches = list(filter(lambda bd: bd["name"] == dev_name, blockdevices))
-        if len(matches) == 0:
-            return None
-        return matches[0]["mountpoint"]
+        for volume_id in rawfile_util.list_all_volumes():
+            img_file = rawfile_util.img_file(volume_id)
+            labels = [volume_id]
+            dev_stat = img_file.stat()
+            dev_size.add_metric(labels, dev_stat.st_size)
+            dev_free.add_metric(labels, dev_stat.st_size - dev_stat.st_blocks * 512)
+            mountpoint = volume_to_mountpoint(img_file)
+            if mountpoint is not None:
+                fs_stat = os.statvfs(mountpoint)
+                fs_size.add_metric(labels, fs_stat.f_frsize * fs_stat.f_blocks)
+                fs_free.add_metric(labels, fs_stat.f_frsize * fs_stat.f_bfree)
 
-    for volume_id in rawfile_util.list_all_volumes():
-        img_file = rawfile_util.img_file(volume_id)
-        labels = {VOLUME_ID: volume_id}
-        dev_stat = img_file.stat()
-        dev_size.labels(**labels).set(dev_stat.st_size)
-        dev_free.labels(**labels).set(dev_stat.st_size - dev_stat.st_blocks * 512)
-        for dev in attached_loops(img_file):
-            mountpoint = dev_to_mountpoint(dev)
-            if mountpoint is None:
-                continue
-            fs_stat = os.statvfs(mountpoint)
-            fs_size.labels(**labels).set(fs_stat.f_frsize * fs_stat.f_blocks)
-            fs_free.labels(**labels).set(fs_stat.f_frsize * fs_stat.f_bfree)
-            break
+        return [fs_size, fs_free, dev_size, dev_free]
+
+
+def volume_to_mountpoint(img_file):
+    for dev in attached_loops(img_file):
+        mountpoint = dev_to_mountpoint(dev)
+        if mountpoint is not None:
+            return mountpoint
+    return None
+
+
+def dev_to_mountpoint(dev_name):
+    try:
+        output = subprocess.run(
+            f"findmnt --json --first-only {dev_name}",
+            shell=True,
+            check=True,
+            capture_output=True,
+        ).stdout.decode()
+        data = json.loads(output)
+        return data["filesystems"][0]["target"]
+    except subprocess.CalledProcessError:
+        return None
 
 
 def expose_metrics():
-    def collector_loop():
-        collect_stats()
-        threading.Timer(10, collector_loop).start()
-
-    collector_loop()
+    REGISTRY.register(VolumeStatsCollector())
     start_http_server(9100)