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 d5d14e993f8..6b8818a4931 100644
--- a/core/src/test/java/org/elasticsearch/monitor/os/OsProbeTests.java
+++ b/core/src/test/java/org/elasticsearch/monitor/os/OsProbeTests.java
@@ -45,18 +45,34 @@ public class OsProbeTests extends ESTestCase {
         OsStats stats = probe.osStats();
         assertNotNull(stats);
         assertThat(stats.getTimestamp(), greaterThan(0L));
-        assertThat(stats.getLoadAverage(), anyOf(equalTo((double) -1), greaterThanOrEqualTo((double) 0)));
+        if (Constants.WINDOWS) {
+            // Load average is always -1 on Windows platforms
+            assertThat(stats.getLoadAverage(), equalTo((double) -1));
+        } else {
+            // Load average can be negative if not available or not computed yet, otherwise it should be >= 0
+            assertThat(stats.getLoadAverage(), anyOf(lessThan((double) 0), greaterThanOrEqualTo((double) 0)));
+        }
 
         assertNotNull(stats.getMem());
-        assertThat(stats.getMem().getTotal().bytes(), anyOf(equalTo(-1L), greaterThan(0L)));
-        assertThat(stats.getMem().getFree().bytes(), anyOf(equalTo(-1L), greaterThan(0L)));
+        assertThat(stats.getMem().getTotal().bytes(), greaterThan(0L));
+        assertThat(stats.getMem().getFree().bytes(), greaterThan(0L));
         assertThat(stats.getMem().getFreePercent(), allOf(greaterThanOrEqualTo((short) 0), lessThanOrEqualTo((short) 100)));
-        assertThat(stats.getMem().getUsed().bytes(), anyOf(equalTo(-1L), greaterThanOrEqualTo(0L)));
+        assertThat(stats.getMem().getUsed().bytes(), greaterThan(0L));
         assertThat(stats.getMem().getUsedPercent(), allOf(greaterThanOrEqualTo((short) 0), lessThanOrEqualTo((short) 100)));
 
         assertNotNull(stats.getSwap());
-        assertThat(stats.getSwap().getTotal().bytes(), anyOf(equalTo(-1L), greaterThanOrEqualTo(0L)));
-        assertThat(stats.getSwap().getFree().bytes(), anyOf(equalTo(-1L), greaterThanOrEqualTo(0L)));
-        assertThat(stats.getSwap().getUsed().bytes(), anyOf(equalTo(-1L), greaterThanOrEqualTo(0L)));
+        assertNotNull(stats.getSwap().getTotal());
+
+        long total = stats.getSwap().getTotal().bytes();
+        if (total > 0) {
+            assertThat(stats.getSwap().getTotal().bytes(), greaterThan(0L));
+            assertThat(stats.getSwap().getFree().bytes(), greaterThan(0L));
+            assertThat(stats.getSwap().getUsed().bytes(), greaterThanOrEqualTo(0L));
+        } else {
+            // On platforms with no swap
+            assertThat(stats.getSwap().getTotal().bytes(), equalTo(0L));
+            assertThat(stats.getSwap().getFree().bytes(), equalTo(0L));
+            assertThat(stats.getSwap().getUsed().bytes(), equalTo(0L));
+        }
     }
 }
diff --git a/core/src/test/java/org/elasticsearch/monitor/process/ProcessProbeTests.java b/core/src/test/java/org/elasticsearch/monitor/process/ProcessProbeTests.java
index 910e51fddad..449ea124afe 100644
--- a/core/src/test/java/org/elasticsearch/monitor/process/ProcessProbeTests.java
+++ b/core/src/test/java/org/elasticsearch/monitor/process/ProcessProbeTests.java
@@ -19,6 +19,7 @@
 
 package org.elasticsearch.monitor.process;
 
+import org.apache.lucene.util.Constants;
 import org.elasticsearch.bootstrap.Bootstrap;
 import org.elasticsearch.test.ESTestCase;
 import org.junit.Test;
@@ -43,14 +44,29 @@ public class ProcessProbeTests extends ESTestCase {
     public void testProcessStats() {
         ProcessStats stats = probe.processStats();
         assertNotNull(stats);
+        assertThat(stats.getTimestamp(), greaterThan(0L));
+
+        if (Constants.WINDOWS) {
+            // Open/Max files descriptors are not supported on Windows platforms
+            assertThat(stats.getOpenFileDescriptors(), equalTo(-1L));
+            assertThat(stats.getMaxFileDescriptors(), equalTo(-1L));
+        } else {
+            assertThat(stats.getOpenFileDescriptors(), greaterThan(0L));
+            assertThat(stats.getMaxFileDescriptors(), greaterThan(0L));
+        }
 
         ProcessStats.Cpu cpu = stats.getCpu();
         assertNotNull(cpu);
-        assertThat(cpu.getPercent(), greaterThanOrEqualTo((short) 0));
-        assertThat(cpu.total, anyOf(equalTo(-1L), greaterThan(0L)));
+
+        // CPU percent can be negative if the system recent cpu usage is not available
+        assertThat(cpu.getPercent(), anyOf(lessThan((short) 0), allOf(greaterThanOrEqualTo((short) 0), lessThanOrEqualTo((short) 100))));
+
+        // CPU time can return -1 if the the platform does not support this operation, let's see which platforms fail
+        assertThat(cpu.total, greaterThan(0L));
 
         ProcessStats.Mem mem = stats.getMem();
         assertNotNull(mem);
-        assertThat(mem.totalVirtual, anyOf(equalTo(-1L), greaterThan(0L)));
+        // Commited total virtual memory can return -1 if not supported, let's see which platforms fail
+        assertThat(mem.totalVirtual, greaterThan(0L));
     }
 }
diff --git a/docs/reference/cluster/nodes-stats.asciidoc b/docs/reference/cluster/nodes-stats.asciidoc
index c2e9daabc58..1425bfee1ee 100644
--- a/docs/reference/cluster/nodes-stats.asciidoc
+++ b/docs/reference/cluster/nodes-stats.asciidoc
@@ -126,7 +126,7 @@ the operating system:
 	Last time the operating system statistics have been refreshed
 
 `os.load_average`::
-	System load average for the last minute
+	System load average for the last minute, or -1 if not supported
 
 `os.mem.total_in_bytes`::
 	Total amount of physical memory in bytes
@@ -170,7 +170,7 @@ the current running process:
 	Maximum number of file descriptors allowed on the system, or -1 if not supported
 
 `process.cpu.percent`::
-	CPU usage in percent
+	CPU usage in percent, or -1 if not known at the time the stats are computed
 
 `process.cpu.total_in_millis`::
 	CPU time (in milliseconds) used by the process on which the Java virtual machine is running, or -1 if not supported