diff --git a/lib/helpers.js b/lib/helpers.js
index a27d0c6e..9e7ab956 100644
--- a/lib/helpers.js
+++ b/lib/helpers.js
@@ -14,7 +14,14 @@ function is_valid_packet(fields) {
         return false;
     }
     // filter out invalid metrics values
-    else if (!fields[0].match(/^([\-\+\d\.]+$)/)) {
+    else if (fields[1] == 'g') {
+        if (!fields[0].match(/^([\-\+\d\.]+$)/)) {
+            return false;
+        } else {
+            return true;
+        }
+    }
+    else if (!fields[0].match(/^([\d\.]+$)/)) {
         return false;
     }
     // filter out malformed sample rates
diff --git a/test/helpers_tests.js b/test/helpers_tests.js
index 4df74959..b2f2c524 100644
--- a/test/helpers_tests.js
+++ b/test/helpers_tests.js
@@ -20,6 +20,30 @@ module.exports = {
     test.done();
   },
 
+  counter_deltas_positive_are_not_valid: function (test) {
+    var res = helpers.is_valid_packet(['+10', 'c']);
+    test.equals(res, false);
+    test.done();
+  },
+
+  counter_deltas_negative_are_not_valid: function (test) {
+    var res = helpers.is_valid_packet(['-10', 'c']);
+    test.equals(res, false);
+    test.done();
+  },
+
+  gauges_delta_positive_are_valid: function (test) {
+    var res = helpers.is_valid_packet(['+10', 'g']);
+    test.equals(res, true);
+    test.done();
+  },
+
+  gauges_delta_negative_are_valid: function (test) {
+    var res = helpers.is_valid_packet(['-10', 'g']);
+    test.equals(res, true);
+    test.done();
+  },
+
   correct_packet: function (test) {
     var res = helpers.is_valid_packet(['345345', 'ms', '@1.0']);
     test.equals(res, true);