diff --git a/core/src/main/java/org/elasticsearch/monitor/os/OsProbe.java b/core/src/main/java/org/elasticsearch/monitor/os/OsProbe.java
index 077b4218fa9..5ee2232068f 100644
--- a/core/src/main/java/org/elasticsearch/monitor/os/OsProbe.java
+++ b/core/src/main/java/org/elasticsearch/monitor/os/OsProbe.java
@@ -119,12 +119,15 @@ public class OsProbe {
             }
             // fallback
         }
+        if (Constants.WINDOWS) {
+            return null;
+        }
         if (getSystemLoadAverage == null) {
             return null;
         }
         try {
             double oneMinuteLoadAverage = (double) getSystemLoadAverage.invoke(osMxBean);
-            return new double[] { oneMinuteLoadAverage, -1, -1 };
+            return new double[] { oneMinuteLoadAverage >= 0 ? oneMinuteLoadAverage : -1, -1, -1 };
         } catch (Throwable t) {
             return null;
         }
diff --git a/core/src/main/java/org/elasticsearch/monitor/os/OsStats.java b/core/src/main/java/org/elasticsearch/monitor/os/OsStats.java
index c419c4f2608..569f8825aa9 100644
--- a/core/src/main/java/org/elasticsearch/monitor/os/OsStats.java
+++ b/core/src/main/java/org/elasticsearch/monitor/os/OsStats.java
@@ -28,6 +28,7 @@ import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentBuilderString;
 
 import java.io.IOException;
+import java.util.Arrays;
 
 /**
  *
@@ -89,7 +90,7 @@ public class OsStats implements Streamable, ToXContent {
         if (cpu != null) {
             builder.startObject(Fields.CPU);
             builder.field(Fields.PERCENT, cpu.getPercent());
-            if (cpu.getLoadAverage() != null) {
+            if (cpu.getLoadAverage() != null && Arrays.stream(cpu.getLoadAverage()).anyMatch(load -> load != -1)) {
                 builder.startObject(Fields.LOAD_AVERAGE);
                 if (cpu.getLoadAverage()[0] != -1) {
                     builder.field(Fields.LOAD_AVERAGE_1M, cpu.getLoadAverage()[0]);
diff --git a/core/src/test/java/org/elasticsearch/monitor/os/OsProbeTests.java b/core/src/test/java/org/elasticsearch/monitor/os/OsProbeTests.java
index 4f4319e212c..2edaad5c4ba 100644
--- a/core/src/test/java/org/elasticsearch/monitor/os/OsProbeTests.java
+++ b/core/src/test/java/org/elasticsearch/monitor/os/OsProbeTests.java
@@ -29,7 +29,6 @@ import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.greaterThan;
 import static org.hamcrest.Matchers.greaterThanOrEqualTo;
 import static org.hamcrest.Matchers.is;
-import static org.hamcrest.Matchers.lessThan;
 import static org.hamcrest.Matchers.lessThanOrEqualTo;
 
 public class OsProbeTests extends ESTestCase {
@@ -56,22 +55,29 @@ public class OsProbeTests extends ESTestCase {
         }
         if (Constants.WINDOWS) {
             // load average is unavailable on Windows
-            if (loadAverage != null) {
-                assertThat(loadAverage[0], equalTo((double) -1));
-                assertThat(loadAverage[1], equalTo((double) -1));
-                assertThat(loadAverage[2], equalTo((double) -1));
-            }
+            assertNull(loadAverage);
         } else if (Constants.LINUX) {
             // we should be able to get the load average
             assertNotNull(loadAverage);
             assertThat(loadAverage[0], greaterThanOrEqualTo((double) 0));
             assertThat(loadAverage[1], greaterThanOrEqualTo((double) 0));
             assertThat(loadAverage[2], greaterThanOrEqualTo((double) 0));
-        } else {
+        } else if (Constants.FREE_BSD) {
+            // five- and fifteen-minute load averages not available if linprocfs is not mounted at /compat/linux/proc
+            assertNotNull(loadAverage);
+            assertThat(loadAverage[0], greaterThanOrEqualTo((double) 0));
+            assertThat(loadAverage[1], anyOf(equalTo((double) -1), greaterThanOrEqualTo((double) 0)));
+            assertThat(loadAverage[2], anyOf(equalTo((double) -1), greaterThanOrEqualTo((double) 0)));
+        } else if (Constants.MAC_OS_X) {
             // one minute load average is available, but 10-minute and 15-minute load averages are not
-            // load average can be negative if not available or not computed yet, otherwise it should be >= 0
+            assertNotNull(loadAverage);
+            assertThat(loadAverage[0], greaterThanOrEqualTo((double) 0));
+            assertThat(loadAverage[1], equalTo((double) -1));
+            assertThat(loadAverage[2], equalTo((double) -1));
+        } else {
+            // unknown system, but the best case is that we have the one-minute load average
             if (loadAverage != null) {
-                assertThat(loadAverage[0], anyOf(lessThan((double) 0), greaterThanOrEqualTo((double) 0)));
+                assertThat(loadAverage[0], anyOf(equalTo((double) -1), greaterThanOrEqualTo((double) 0)));
                 assertThat(loadAverage[1], equalTo((double) -1));
                 assertThat(loadAverage[2], equalTo((double) -1));
             }