diff --git a/src/se/hal/page/PCOverviewHttpPage.java b/src/se/hal/page/PCOverviewHttpPage.java
index b06873a5..fdbc5b1f 100755
--- a/src/se/hal/page/PCOverviewHttpPage.java
+++ b/src/se/hal/page/PCOverviewHttpPage.java
@@ -99,7 +99,7 @@ public class PCOverviewHttpPage extends HalHttpPage implements HalHttpPage.HalJs
         for (AggregateDataListSqlResult.AggregateData data : dataList) {
             DataNode dataNode = new DataNode(DataNode.DataType.Map);
             dataNode.set("time", data.timestamp);
-            if (Float.isNaN(data.data))
+            if (data.data == null || Float.isNaN(data.data))
                 dataNode.set("" + data.id, (String)null);
             else
                 dataNode.set("" + data.id, data.data);
diff --git a/src/se/hal/util/AggregateDataListSqlResult.java b/src/se/hal/util/AggregateDataListSqlResult.java
index 2f98554d..47299289 100755
--- a/src/se/hal/util/AggregateDataListSqlResult.java
+++ b/src/se/hal/util/AggregateDataListSqlResult.java
@@ -17,10 +17,10 @@ public class AggregateDataListSqlResult implements SQLResultHandler<ArrayList<Ag
 	public static class AggregateData {
         public int id;
 		public long timestamp;
-		public float data;
+		public Float data;
 		public String username;
 
-		public AggregateData(int id, long time, float data, String uname) {
+		public AggregateData(int id, long time, Float data, String uname) {
             this.id = id;
 			this.timestamp = time;
 			this.data = data;
@@ -76,7 +76,7 @@ public class AggregateDataListSqlResult implements SQLResultHandler<ArrayList<Ag
 
 			//add null data point to list if one or more periods of data is missing before this
 			if(previousTimestampEnd != -1 && previousTimestampEnd+1 < timestampStart){
-				list.add(new AggregateData(id, previousTimestampEnd+1, Float.NaN, username));
+				list.add(new AggregateData(id, previousTimestampEnd+1, null /*Float.NaN*/, username));
 			}
 
 			list.add(new AggregateData(id, timestampEnd, (estimatedData/1000f), username));	//add this data point to list