diff --git a/infra/values/base/opencost-values.yaml b/infra/values/base/opencost-values.yaml
index dde13fb..a6d8142 100644
--- a/infra/values/base/opencost-values.yaml
+++ b/infra/values/base/opencost-values.yaml
@@ -4,14 +4,17 @@ opencost:
     extraEnv:
       EMIT_KSM_V1_METRICS: "false"
       EMIT_KSM_V1_METRICS_ONLY: "true"
-    prometheus:
-      internal:
-        enabled: true
-        serviceName: prometheus-server
-        namespaceName: monitoring
-        port: 80
     # Cloud-specific pricing is in per-cluster value overrides
     # (e.g. infra/values/upc-dev/opencost-values.yaml)
+  # NOTE: `prometheus` is a sibling of `exporter` under `opencost` in the
+  # chart's values schema - nesting it inside `exporter` silently falls back
+  # to the chart default namespace (prometheus-system).
+  prometheus:
+    internal:
+      enabled: true
+      serviceName: prometheus-server
+      namespaceName: monitoring
+      port: 80
   ui:
     enabled: false
 service: