diff --git a/src/main/java/com/splunk/logging/serialization/HecJsonSerializer.java b/src/main/java/com/splunk/logging/serialization/HecJsonSerializer.java
index 64ba99d8..cdc4b06e 100644
--- a/src/main/java/com/splunk/logging/serialization/HecJsonSerializer.java
+++ b/src/main/java/com/splunk/logging/serialization/HecJsonSerializer.java
@@ -63,6 +63,10 @@ public String serialize(HttpEventCollectorEventInfo info) {
         } else {
             event.put("event", info);
         }
+        if (!event.containsKey("time") && info.getTime() > 0) {
+            // We haven't figured any other time - so use the time from the event.
+            event.put("time", String.format(Locale.US, "%.3f", info.getTime()));
+        }
         return gson.toJson(event);
     }
 
diff --git a/src/test/java/HecJsonSerializerTest.java b/src/test/java/HecJsonSerializerTest.java
new file mode 100644
index 00000000..fee50429
--- /dev/null
+++ b/src/test/java/HecJsonSerializerTest.java
@@ -0,0 +1,77 @@
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.splunk.logging.EventBodySerializer;
+import com.splunk.logging.HttpEventCollectorEventInfo;
+import com.splunk.logging.serialization.HecJsonSerializer;
+import org.junit.Assert;
+import org.junit.Test;
+
+@SuppressWarnings("unchecked")
+public class HecJsonSerializerTest {
+    private final Gson gson = new GsonBuilder()
+        .disableHtmlEscaping()
+        .create();
+
+    private final HttpEventCollectorEventInfo event = new HttpEventCollectorEventInfo(1636473405870L, "INFO", "Test Message", "MyLogger", "Thread", Collections.emptyMap(), null, null);
+
+    @Test
+    public void itShouldPopulateTheTime() {
+        HecJsonSerializer serializer = new HecJsonSerializer(Collections.emptyMap());
+        String result = serializer.serialize(event);
+        Map<String, Object> map = (Map<String, Object>) gson.fromJson(result, Map.class);
+        Assert.assertEquals("1636473405.870", map.get("time"));
+    }
+
+    @Test
+    @SuppressWarnings("unchecked")
+    public void itShouldNotPopulateTheTimeIfAlreadyPopulated() {
+        HecJsonSerializer serializer = new HecJsonSerializer(Collections.singletonMap("time", "1234.567"));
+        String result = serializer.serialize(event);
+        Map<String, Object> map = (Map<String, Object>) gson.fromJson(result, Map.class);
+        Assert.assertEquals("1234.567", map.get("time"));
+    }
+
+    @Test
+    @SuppressWarnings("unchecked")
+    public void itShouldNotPopulateTheTimeIfHeaderPopulates() {
+        HecJsonSerializer serializer = new HecJsonSerializer(Collections.emptyMap());
+        serializer.setEventHeaderSerializer((eventInfo, metadata) -> new HashMap<>(Collections.singletonMap("time", "12345.678")));
+        String result = serializer.serialize(event);
+        Map<String, Object> map = (Map<String, Object>) gson.fromJson(result, Map.class);
+        Assert.assertEquals("12345.678", map.get("time"));
+    }
+
+    @Test
+    @SuppressWarnings("unchecked")
+    public void itShouldNotPopulateTheTimeIfBodyPopulates() {
+        HecJsonSerializer serializer = new HecJsonSerializer(Collections.emptyMap());
+        serializer.setEventBodySerializer(new EventBodySerializer() {
+            @Override
+            public String serializeEventBody(final HttpEventCollectorEventInfo eventInfo, final Object formattedMessage) {
+                return "XXX";
+            }
+
+            @Override
+            public double getEventTime(final HttpEventCollectorEventInfo eventInfo) {
+                return 1.0d;
+            }
+        });
+        String result = serializer.serialize(event);
+        Map<String, Object> map = (Map<String, Object>) gson.fromJson(result, Map.class);
+        Assert.assertEquals("1.000", map.get("time"));
+    }
+
+    @Test
+    @SuppressWarnings("unchecked")
+    public void itShouldPopulateTheTimeIfBodyOverrideDoesntSetTime() {
+        HecJsonSerializer serializer = new HecJsonSerializer(Collections.emptyMap());
+        serializer.setEventBodySerializer((eventInfo, formattedMessage) -> "XXX");
+        String result = serializer.serialize(event);
+        Map<String, Object> map = (Map<String, Object>) gson.fromJson(result, Map.class);
+        Assert.assertEquals("1636473405.870", map.get("time"));
+    }
+}