diff --git a/public/app/plugins/datasource/prometheus/datasource.ts b/public/app/plugins/datasource/prometheus/datasource.ts
index 569243067de..da9dba15f33 100644
--- a/public/app/plugins/datasource/prometheus/datasource.ts
+++ b/public/app/plugins/datasource/prometheus/datasource.ts
@@ -56,7 +56,7 @@ export class PrometheusDatasource extends DataSourceWithBackend<PromQuery, PromO
   withCredentials: any;
   metricsNameCache = new LRU<string, string[]>(10);
   interval: string;
-  queryTimeout: string;
+  queryTimeout: string | undefined;
   httpMethod: string;
   languageProvider: PrometheusLanguageProvider;
   exemplarTraceIdDestinations: ExemplarTraceIdDestination[] | undefined;
@@ -80,7 +80,9 @@ export class PrometheusDatasource extends DataSourceWithBackend<PromQuery, PromO
     this.interval = instanceSettings.jsonData.timeInterval || '15s';
     this.queryTimeout = instanceSettings.jsonData.queryTimeout;
     this.httpMethod = instanceSettings.jsonData.httpMethod || 'POST';
-    this.directUrl = instanceSettings.jsonData.directUrl;
+    // `directUrl` is never undefined, we set it at https://github.com/grafana/grafana/blob/main/pkg/api/frontendsettings.go#L108
+    // here we "fall back" to this.url to make typescript happy, but it should never happen
+    this.directUrl = instanceSettings.jsonData.directUrl ?? this.url;
     this.exemplarTraceIdDestinations = instanceSettings.jsonData.exemplarTraceIdDestinations;
     this.ruleMappings = {};
     this.languageProvider = new PrometheusLanguageProvider(this);
diff --git a/public/app/plugins/datasource/prometheus/types.ts b/public/app/plugins/datasource/prometheus/types.ts
index fa84bcad94b..da95b00306a 100644
--- a/public/app/plugins/datasource/prometheus/types.ts
+++ b/public/app/plugins/datasource/prometheus/types.ts
@@ -20,10 +20,10 @@ export interface PromQuery extends DataQuery {
 }
 
 export interface PromOptions extends DataSourceJsonData {
-  timeInterval: string;
-  queryTimeout: string;
-  httpMethod: string;
-  directUrl: string;
+  timeInterval?: string;
+  queryTimeout?: string;
+  httpMethod?: string;
+  directUrl?: string;
   customQueryParameters?: string;
   disableMetricsLookup?: boolean;
   exemplarTraceIdDestinations?: ExemplarTraceIdDestination[];