diff --git a/CHANGELOG.md b/CHANGELOG.md
index 023b88e..8b9aac8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# v3.3.3
+
+* add: custom metric support
+
 # v3.3.2
 
 * fix: put locking in snapshot handlers
diff --git a/circonus-gometrics.go b/circonus-gometrics.go
index 125a79c..0d2cfdc 100644
--- a/circonus-gometrics.go
+++ b/circonus-gometrics.go
@@ -30,10 +30,13 @@
 package circonusgometrics
 
 import (
+	"fmt"
 	"io/ioutil"
 	"log"
 	"os"
+	"regexp"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 
@@ -43,6 +46,43 @@ import (
 
 const (
 	defaultFlushInterval = "10s" // 10 * time.Second
+
+	// MetricTypeInt32 reconnoiter
+	MetricTypeInt32 = "i"
+
+	// MetricTypeUint32 reconnoiter
+	MetricTypeUint32 = "I"
+
+	// MetricTypeInt64 reconnoiter
+	MetricTypeInt64 = "l"
+
+	// MetricTypeUint64 reconnoiter
+	MetricTypeUint64 = "L"
+
+	// MetricTypeFloat64 reconnoiter
+	MetricTypeFloat64 = "n"
+
+	// MetricTypeString reconnoiter
+	MetricTypeString = "s"
+
+	// MetricTypeHistogram reconnoiter
+	MetricTypeHistogram = "h"
+
+	// MetricTypeCumulativeHistogram reconnoiter
+	MetricTypeCumulativeHistogram = "H"
+)
+
+var (
+	metricTypeRx = regexp.MustCompile(`^[` + strings.Join([]string{
+		MetricTypeInt32,
+		MetricTypeUint32,
+		MetricTypeInt64,
+		MetricTypeUint64,
+		MetricTypeFloat64,
+		MetricTypeString,
+		MetricTypeHistogram,
+		MetricTypeCumulativeHistogram,
+	}, "") + `]$`)
 )
 
 // Logger facilitates use of any logger supporting the required methods
@@ -120,6 +160,9 @@ type CirconusMetrics struct {
 
 	textFuncs map[string]func() string
 	tfm       sync.Mutex
+
+	custom map[string]Metric
+	custm  sync.Mutex
 }
 
 // NewCirconusMetrics returns a CirconusMetrics instance
@@ -142,6 +185,7 @@ func New(cfg *Config) (*CirconusMetrics, error) {
 		histograms:   make(map[string]*Histogram),
 		text:         make(map[string]string),
 		textFuncs:    make(map[string]func() string),
+		custom:       make(map[string]Metric),
 		lastMetrics:  &prevMetrics{},
 	}
 
@@ -247,3 +291,16 @@ func (m *CirconusMetrics) Start() {
 func (m *CirconusMetrics) Ready() bool {
 	return m.check.IsReady()
 }
+
+// Custom adds a user defined metric
+func (m *CirconusMetrics) Custom(metricName string, metric Metric) error {
+	if !metricTypeRx.MatchString(metric.Type) {
+		return fmt.Errorf("unrecognized circonus metric type (%s)", metric.Type)
+	}
+
+	m.custm.Lock()
+	m.custom[metricName] = metric
+	m.custm.Unlock()
+
+	return nil
+}
diff --git a/metric_output.go b/metric_output.go
index d73c440..48e8e59 100644
--- a/metric_output.go
+++ b/metric_output.go
@@ -28,9 +28,18 @@ func (m *CirconusMetrics) packageMetrics() (map[string]*apiclient.CheckBundleMet
 
 	ts := makeTimestamp(time.Now())
 
-	counters, gauges, histograms, text := m.snapshot()
 	newMetrics := make(map[string]*apiclient.CheckBundleMetric)
-	output := make(Metrics, len(counters)+len(gauges)+len(histograms)+len(text))
+	counters, gauges, histograms, text := m.snapshot()
+	m.custm.Lock()
+	output := make(Metrics, len(counters)+len(gauges)+len(histograms)+len(text)+len(m.custom))
+	if len(m.custom) > 0 {
+		// add and reset any custom metrics
+		for mn, mv := range m.custom {
+			output[mn] = mv
+		}
+		m.custom = make(map[string]Metric)
+	}
+	m.custm.Unlock()
 	for name, value := range counters {
 		send := m.check.IsMetricActive(name)
 		if !send && m.check.ActivateMetric(name) {