diff --git a/owrx/controllers/metrics.py b/owrx/controllers/metrics.py
index 4d41a2a2..2b2614c6 100644
--- a/owrx/controllers/metrics.py
+++ b/owrx/controllers/metrics.py
@@ -21,7 +21,7 @@ class MetricsController(Controller):
             else:
                 raise ValueError("Unexpected metric type for metric {}".format(repr(metric)))
 
-            return "{key} {value}".format(key=key.replace(".", "_"), value=value)
+            return "{key} {value}".format(key=re.sub('[^a-zA-Z0-9:_]', '_', key), value=value)
 
         data = ["# https://prometheus.io/docs/instrumenting/exposition_formats/"] + [
             prometheusFormat(k, v) for k, v in metrics.items()