diff --git a/src/main/java/info/ganglia/gmetric4j/gmetric/GMetricSlope.java b/src/main/java/info/ganglia/gmetric4j/gmetric/GMetricSlope.java
index 1b757a9..ad73834 100644
--- a/src/main/java/info/ganglia/gmetric4j/gmetric/GMetricSlope.java
+++ b/src/main/java/info/ganglia/gmetric4j/gmetric/GMetricSlope.java
@@ -10,11 +10,13 @@
  * @author humphrej
  */
 public enum GMetricSlope {
-    //zero|positive|negative|both
+    //zero|positive|negative|both|derivative
     ZERO(0),
     POSITIVE(1),
     NEGATIVE(2),
-    BOTH(3);
+    BOTH(3),
+    UNSPECIFIED(4),
+    DERIVATIVE(5);
     
     private int gangliaSlope ;