diff --git a/cloudkitty/collector/prometheus.py b/cloudkitty/collector/prometheus.py
index 21101753..88cfce9e 100644
--- a/cloudkitty/collector/prometheus.py
+++ b/cloudkitty/collector/prometheus.py
@@ -130,7 +130,7 @@ class PrometheusCollector(collector.BaseCollector):
         """
         metadata = {}
         for meta in self.conf[metric_name]['metadata']:
-            metadata[meta] = data['metric'][meta]
+            metadata[meta] = data['metric'].get(meta, '')
 
         groupby = {scope_key: scope_id}
         for meta in self.conf[metric_name]['groupby']:
diff --git a/releasenotes/notes/prometheus-collector-empty-meta-12402d8f0254c011.yaml b/releasenotes/notes/prometheus-collector-empty-meta-12402d8f0254c011.yaml
new file mode 100644
index 00000000..fb415f53
--- /dev/null
+++ b/releasenotes/notes/prometheus-collector-empty-meta-12402d8f0254c011.yaml
@@ -0,0 +1,5 @@
+---
+issues:
+  - |
+    Fixes exceptions in Prometheus collector when metadata defined in
+    ``metrics.yml`` is not present on metrics retrieved from Prometheus.