diff --git a/public/app/plugins/datasource/prometheus/datasource.test.ts b/public/app/plugins/datasource/prometheus/datasource.test.ts
index e440be233b1..645732755b6 100644
--- a/public/app/plugins/datasource/prometheus/datasource.test.ts
+++ b/public/app/plugins/datasource/prometheus/datasource.test.ts
@@ -1130,9 +1130,10 @@ describe('PrometheusDatasource', () => {
         ],
         interval: '5s',
       };
-      const end = 7 * 24 * 60 * 60;
+      let end = 7 * 24 * 60 * 60;
+      end -= end % 55;
       const start = 0;
-      const urlExpected = 'proxied/api/v1/query_range?query=test' + '&start=' + start + '&end=' + end + '&step=60';
+      const urlExpected = 'proxied/api/v1/query_range?query=test' + '&start=' + start + '&end=' + end + '&step=55';
       getBackendSrvMock().datasourceRequest = jest.fn(() => Promise.resolve(response));
       ds.query(query as any);
       const res = (getBackendSrvMock().datasourceRequest as jest.Mock<any>).mock.calls[0][0];
@@ -1379,7 +1380,8 @@ describe('PrometheusDatasource', () => {
           __interval_ms: { text: 5 * 1000, value: 5 * 1000 },
         },
       };
-      const end = 7 * 24 * 60 * 60;
+      let end = 7 * 24 * 60 * 60;
+      end -= end % 55;
       const start = 0;
       const urlExpected =
         'proxied/api/v1/query_range?query=' +
@@ -1388,7 +1390,7 @@ describe('PrometheusDatasource', () => {
         start +
         '&end=' +
         end +
-        '&step=60';
+        '&step=55';
       getBackendSrvMock().datasourceRequest = jest.fn(() => Promise.resolve(response));
       templateSrv.replace = jest.fn(str => str);
       ds.query(query as any);
diff --git a/public/app/plugins/datasource/prometheus/datasource.ts b/public/app/plugins/datasource/prometheus/datasource.ts
index acde4c0d6a1..454ef8e164d 100644
--- a/public/app/plugins/datasource/prometheus/datasource.ts
+++ b/public/app/plugins/datasource/prometheus/datasource.ts
@@ -396,11 +396,9 @@ export class PrometheusDatasource extends DataSourceApi<PromQuery, PromOptions>
 
   adjustInterval(interval: number, minInterval: number, range: number, intervalFactor: number) {
     // Prometheus will drop queries that might return more than 11000 data points.
-    // Calibrate interval if it is too small.
-    if (interval !== 0 && range / intervalFactor / interval > 11000) {
-      interval = Math.ceil(range / intervalFactor / 11000);
-    }
-    return Math.max(interval * intervalFactor, minInterval, 1);
+    // Calculate a safe interval as an additional minimum to take into account.
+    const safeInterval = Math.ceil(range / 11000);
+    return Math.max(interval * intervalFactor, minInterval, safeInterval, 1);
   }
 
   performTimeSeriesQuery(query: PromQueryRequest, start: number, end: number) {