diff --git a/src/gandi_pyramid_prometheus/prometheus.py b/src/gandi_pyramid_prometheus/prometheus.py
index b715e9b..1919924 100644
--- a/src/gandi_pyramid_prometheus/prometheus.py
+++ b/src/gandi_pyramid_prometheus/prometheus.py
@@ -25,6 +25,8 @@ def includeme(config):
 
     IS_MULTIPROC = asbool(
         config.registry.settings.get("prometheus.use_multiproc", "false")
+    ) and bool(
+        {"PROMETHEUS_MULTIPROC_DIR", "prometheus_multiproc_dir"} & set(os.environ)
     )
 
     kwargs = {