--- a/host-cpu/client-core/src/main/java/com/redhat/thermostat/host/cpu/client/core/internal/HostCpuController.java	Thu Jun 23 11:17:14 2016 -0400
+++ b/host-cpu/client-core/src/main/java/com/redhat/thermostat/host/cpu/client/core/internal/HostCpuController.java	Thu Jun 23 12:04:07 2016 -0400
@@ -139,6 +139,10 @@
     private void doCpuChartUpdate() {
         CpuStat oldest = cpuStatDAO.getOldest(ref);
         CpuStat newest = cpuStatDAO.getNewest(ref);
+        // Do nothing if there is no data
+        if (oldest == null || newest == null) {
+            return;
+        }
 
         final List<CpuStat> cpuStats = new ArrayList<>();
 

--- a/host-cpu/client-core/src/test/java/com/redhat/thermostat/host/cpu/client/core/internal/HostCpuControllerTest.java	Thu Jun 23 11:17:14 2016 -0400
+++ b/host-cpu/client-core/src/test/java/com/redhat/thermostat/host/cpu/client/core/internal/HostCpuControllerTest.java	Thu Jun 23 12:04:07 2016 -0400
@@ -52,7 +52,6 @@
 import java.util.concurrent.TimeUnit;
 
 import org.junit.After;
-import org.junit.Before;
 import org.junit.Test;
 import org.mockito.ArgumentCaptor;
 
@@ -86,8 +85,7 @@
     private Runnable timerAction;
 
     @SuppressWarnings({ "rawtypes", "unchecked" })
-    @Before
-    public void setUp() {
+    public void setUpWithCpuDAO(CpuStatDAO cpuStatDAO) {
         // Setup timer.
         timer = mock(Timer.class);
         ArgumentCaptor<Runnable> actionCaptor = ArgumentCaptor.forClass(Runnable.class);
@@ -103,15 +101,6 @@
         HostInfoDAO hostInfoDAO = mock(HostInfoDAO.class);
         when(hostInfoDAO.getHostInfo(any(HostRef.class))).thenReturn(hostInfo);
 
-        CpuStat cpuStat1 = new CpuStat("foo", 1l, new double[] {10.0, 20.0, 30.0});
-        CpuStat cpuStat2 = new CpuStat("foo", 2l, new double[] {15.0, 25.0, 35.0});
-        CpuStatDAO cpuStatDAO = mock(CpuStatDAO.class);
-
-        when(cpuStatDAO.getOldest(any(HostRef.class))).thenReturn(cpuStat1);
-        when(cpuStatDAO.getNewest(any(HostRef.class))).thenReturn(cpuStat2);
-
-        when(cpuStatDAO.getCpuStats(any(HostRef.class), anyLong(), anyLong())).thenReturn(Arrays.asList(cpuStat1, cpuStat2));
-
         // Set up View
         view = mock(HostCpuView.class);
         when(view.getUserDesiredDuration()).thenReturn(new Duration(10, TimeUnit.MINUTES));
@@ -138,6 +127,8 @@
 
     @Test
     public void testTimer() {
+        setUpWithCpuDAO(mock(CpuStatDAO.class));
+        
         viewListener.actionPerformed(new ActionEvent<>(view, HostCpuView.Action.VISIBLE));
 
         verify(timer).setAction(isNotNull(Runnable.class));
@@ -155,6 +146,17 @@
     @SuppressWarnings("unchecked")
     @Test
     public void testTimerAction() {
+        CpuStat cpuStat1 = new CpuStat("foo", 1l, new double[] {10.0, 20.0, 30.0});
+        CpuStat cpuStat2 = new CpuStat("foo", 2l, new double[] {15.0, 25.0, 35.0});
+        CpuStatDAO cpuStatDAO = mock(CpuStatDAO.class);
+
+        when(cpuStatDAO.getOldest(any(HostRef.class))).thenReturn(cpuStat1);
+        when(cpuStatDAO.getNewest(any(HostRef.class))).thenReturn(cpuStat2);
+
+        when(cpuStatDAO.getCpuStats(any(HostRef.class), anyLong(), anyLong())).thenReturn(Arrays.asList(cpuStat1, cpuStat2));
+        
+        setUpWithCpuDAO(cpuStatDAO);
+        
         timerAction.run();
         verify(view).setCpuModel("fluffCpu1");
         verify(view).setCpuCount("12345");
@@ -168,5 +170,16 @@
         assertEquals(2, cpuLoadData.get(1).getTimeInMillis());
         assertEquals(15.0, cpuLoadData.get(1).getData().doubleValue(), 0.0001);
     }
+    
+    /**
+     * Verifies that chart update does not throw a NPE due to no CPU stats
+     * available.
+     */
+    @Test
+    public void testViewUpdateNoCPUDatat() {
+        // will return null on getlattest/getOldest
+        setUpWithCpuDAO(mock(CpuStatDAO.class));
+        timerAction.run();
+    }
 }