diff --git a/public/app/plugins/datasource/prometheus/datasource.js b/public/app/plugins/datasource/prometheus/datasource.js
index c86fa2806d3..1b083d16956 100644
--- a/public/app/plugins/datasource/prometheus/datasource.js
+++ b/public/app/plugins/datasource/prometheus/datasource.js
@@ -212,7 +212,7 @@ function (angular, _, moment, dateMath) {
         sec = 1;
       }
 
-      return Math.ceil(sec * intervalFactor) + 's';
+      return Math.ceil(sec * intervalFactor);
     };
 
     function transformMetricData(md, options) {
diff --git a/public/app/plugins/datasource/prometheus/specs/datasource_specs.ts b/public/app/plugins/datasource/prometheus/specs/datasource_specs.ts
index 2ac4992edef..58034d09cac 100644
--- a/public/app/plugins/datasource/prometheus/specs/datasource_specs.ts
+++ b/public/app/plugins/datasource/prometheus/specs/datasource_specs.ts
@@ -19,7 +19,7 @@ describe('PrometheusDatasource', function() {
     var results;
     var urlExpected = 'proxied/api/v1/query_range?query=' +
                       encodeURIComponent('test{job="testjob"}') +
-                      '&start=1443438675&end=1443460275&step=60s';
+                      '&start=1443438675&end=1443460275&step=60';
     var query = {
       range: { from: moment(1443438674760), to: moment(1443460274760) },
       targets: [{ expr: 'test{job="testjob"}' }],