diff --git a/CHANGELOG.md b/CHANGELOG.md
index 70bd5222a91..58b08eacb4f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 - [Issue #1126](https://github.com/grafana/grafana/issues/1126). InfluxDB: Support more than 10 series name segments when using alias ``$number`` patterns
 
 **Fixes**
+- [Issue #1251](https://github.com/grafana/grafana/issues/1251). Graph: Fix for y axis and scaled units (GiB etc) caused rounding, for example 400 GiB instead of 378 GiB
 - [Issue #1199](https://github.com/grafana/grafana/issues/1199). Graph: fix for series tooltip when one series is hidden/disabled
 - [Issue #1207](https://github.com/grafana/grafana/issues/1207). Graphite: movingAverage / movingMedian parameter type impovement, now handles int and interval parameter
 
diff --git a/src/app/components/kbn.js b/src/app/components/kbn.js
index ecef4bd164e..aedfbb90f17 100644
--- a/src/app/components/kbn.js
+++ b/src/app/components/kbn.js
@@ -339,7 +339,7 @@ function($, _, moment) {
       return "";
     }
 
-    var factor = decimals ? Math.pow(10, decimals) : 1;
+    var factor = decimals ? Math.pow(10, Math.max(0, decimals)) : 1;
     var formatted = String(Math.round(value * factor) / factor);
 
     // if exponent return directly
diff --git a/src/test/specs/kbn-format-specs.js b/src/test/specs/kbn-format-specs.js
index e92e6d0ceec..785d9376411 100644
--- a/src/test/specs/kbn-format-specs.js
+++ b/src/test/specs/kbn-format-specs.js
@@ -29,6 +29,13 @@ define([
   describeValueFormat('ns', 25, 1, 0, '25 ns');
   describeValueFormat('ns', 2558, 50, 0, '2.56 µs');
 
+  describe('kbn.toFixed and negative decimals', function() {
+    it('should treat as zero decimals', function() {
+      var str = kbn.toFixed(186.123, -2);
+      expect(str).to.be('186');
+    });
+  });
+
   describe('calculateInterval', function() {
     it('1h 100 resultion', function() {
       var range = { from: kbn.parseDate('now-1h'), to: kbn.parseDate('now') };