diff --git a/app/src/main/java/info/nightscout/androidaps/plugins/IobCobCalculator/IobCobCalculatorPlugin.java b/app/src/main/java/info/nightscout/androidaps/plugins/IobCobCalculator/IobCobCalculatorPlugin.java
index 82630b81ae..f067b69670 100644
--- a/app/src/main/java/info/nightscout/androidaps/plugins/IobCobCalculator/IobCobCalculatorPlugin.java
+++ b/app/src/main/java/info/nightscout/androidaps/plugins/IobCobCalculator/IobCobCalculatorPlugin.java
@@ -284,7 +284,7 @@ public class IobCobCalculatorPlugin extends PluginBase {
         }
 
         // Normalize bucketed data
-        for (int i = bucketed_data.size() - 2; i > 0; i--) {
+        for (int i = bucketed_data.size() - 2; i >= 0; i--) {
             BgReading current = bucketed_data.get(i);
             BgReading previous = bucketed_data.get(i + 1);
             long msecDiff = current.date - previous.date;
diff --git a/app/src/test/java/info/nightscout/androidaps/plugins/IobCobCalculatorPlugin/IobCobCalculatorPluginTest.java b/app/src/test/java/info/nightscout/androidaps/plugins/IobCobCalculatorPlugin/IobCobCalculatorPluginTest.java
index 7fde0b0465..d89e637557 100644
--- a/app/src/test/java/info/nightscout/androidaps/plugins/IobCobCalculatorPlugin/IobCobCalculatorPluginTest.java
+++ b/app/src/test/java/info/nightscout/androidaps/plugins/IobCobCalculatorPlugin/IobCobCalculatorPluginTest.java
@@ -146,11 +146,12 @@ public class IobCobCalculatorPluginTest {
         bgReadingList.add(new BgReading().date(T.mins(15).msecs() + T.secs(10).msecs()).value(100));
         bgReadingList.add(new BgReading().date(T.mins(10).msecs() + T.secs(10).msecs()).value(100));
         bgReadingList.add(new BgReading().date(T.mins(5).msecs() - T.secs(10).msecs()).value(100));
+        bgReadingList.add(new BgReading().date(T.mins(0).msecs()).value(100));
 
         iobCobCalculatorPlugin.setBgReadings(bgReadingList);
         iobCobCalculatorPlugin.createBucketedData();
 
-        Assert.assertEquals(false, iobCobCalculatorPlugin.isAbout5minData()); // too much drift
+        Assert.assertEquals(true, iobCobCalculatorPlugin.isAbout5minData());
         Assert.assertEquals(T.mins(20).msecs(), iobCobCalculatorPlugin.getBucketedData().get(0).date);
         Assert.assertEquals(T.mins(15).msecs(), iobCobCalculatorPlugin.getBucketedData().get(1).date);
         Assert.assertEquals(T.mins(10).msecs(), iobCobCalculatorPlugin.getBucketedData().get(2).date);