diff --git a/charts/prometheus/templates/pdb.yaml b/charts/prometheus/templates/pdb.yaml
index eacd51dcb326..dff9284f0c34 100644
--- a/charts/prometheus/templates/pdb.yaml
+++ b/charts/prometheus/templates/pdb.yaml
@@ -11,10 +11,16 @@ spec:
   selector:
     matchLabels:
       {{- include "prometheus.server.matchLabels" . | nindent 6 }}
-  {{- if $pdbSpec.minAvailable }}
+  {{- if not (or (hasKey $pdbSpec "minAvailable") (hasKey $pdbSpec "maxUnavailable")) }}
+  maxUnavailable: 1
+  {{- end }}
+  {{- if hasKey $pdbSpec "minAvailable" }}
   minAvailable: {{ $pdbSpec.minAvailable }}
   {{- end }}
-  {{- if $pdbSpec.maxUnavailable }}
+  {{- if hasKey $pdbSpec "maxUnavailable" }}
   maxUnavailable: {{ $pdbSpec.maxUnavailable }}
   {{- end }}
+  {{- if hasKey $pdbSpec "unhealthyPodEvictionPolicy" }}
+  unhealthyPodEvictionPolicy: {{ $pdbSpec.unhealthyPodEvictionPolicy }}
+  {{- end }}}}
 {{- end }}