diff --git a/prometheus.cabal b/prometheus.cabal
--- a/prometheus.cabal
+++ b/prometheus.cabal
@@ -1,12 +1,12 @@
 name:                prometheus
-version:             0.4.1
+version:             0.4.2
 synopsis:            Prometheus Haskell Client
-homepage:            http://github.com/LukeHoersten/prometheus#readme
-bug-reports:         http://github.com/LukeHoersten/prometheus/issues
+homepage:            http://github.com/bitnomial/prometheus
+bug-reports:         http://github.com/bitnomial/prometheus/issues
 license:             BSD3
 license-file:        LICENSE
 author:              Luke Hoersten
-maintainer:          luke@hoersten.org, opensource@bitnomial.com
+maintainer:          luke@bitnomial.com, opensource@bitnomial.com
 copyright:           Bitnomial, Inc. (c) 2016
 category:            Metrics, Monitoring, Web, System
 build-type:          Simple
@@ -74,7 +74,7 @@
                  , System.Metrics.Prometheus.RegistryT
 
   build-depends: atomic-primops >= 0.8  && < 0.9
-               , base           >= 4.7  && < 4.10
+               , base           >= 4.7  && < 4.11
                , bytestring     >= 0.10 && < 0.11
                , containers     >= 0.5  && < 0.6
                , http-types     >= 0.8  && < 0.10
@@ -85,4 +85,4 @@
 
 source-repository head
   type:     git
-  location: https://github.com/LukeHoersten/prometheus
+  location: https://github.com/bitnomial/prometheus
diff --git a/src/System/Metrics/Prometheus/Metric/Counter.hs b/src/System/Metrics/Prometheus/Metric/Counter.hs
--- a/src/System/Metrics/Prometheus/Metric/Counter.hs
+++ b/src/System/Metrics/Prometheus/Metric/Counter.hs
@@ -5,11 +5,11 @@
        , add
        , inc
        , sample
+       , addAndSample
        ) where
 
 
-import           Data.Atomics.Counter (AtomicCounter, incrCounter_, newCounter,
-                                       readCounter)
+import           Data.Atomics.Counter (AtomicCounter, incrCounter, newCounter)
 
 
 newtype Counter = Counter { unCounter :: AtomicCounter }
@@ -20,14 +20,16 @@
 new = Counter <$> newCounter 0
 
 
-add :: Int -> Counter -> IO ()
-add by | by >= 0 = incrCounter_ by . unCounter
-       | otherwise = error "must be >= 0"
+addAndSample :: Int -> Counter -> IO CounterSample
+addAndSample by | by >= 0 = fmap CounterSample . incrCounter by . unCounter
+                | otherwise = error "must be >= 0"
 
+add :: Int -> Counter -> IO ()
+add by c = addAndSample by c >> pure ()
 
 inc :: Counter -> IO ()
 inc = add 1
 
 
 sample :: Counter -> IO CounterSample
-sample = fmap CounterSample . readCounter . unCounter
+sample = addAndSample 0
diff --git a/src/System/Metrics/Prometheus/Metric/Gauge.hs b/src/System/Metrics/Prometheus/Metric/Gauge.hs
--- a/src/System/Metrics/Prometheus/Metric/Gauge.hs
+++ b/src/System/Metrics/Prometheus/Metric/Gauge.hs
@@ -8,6 +8,7 @@
        , dec
        , set
        , sample
+       , modifyAndSample
        ) where
 
 import           Data.IORef (IORef, atomicModifyIORef', atomicWriteIORef,
@@ -22,13 +23,17 @@
 new = Gauge <$> newIORef 0
 
 
+modifyAndSample :: (Double -> (Double, a)) -> Gauge -> IO a
+modifyAndSample f = flip atomicModifyIORef' f . unGauge
+
+
 add :: Double -> Gauge -> IO ()
-add x = flip atomicModifyIORef' f . unGauge
+add x = modifyAndSample f
   where f v = (v + x, ())
 
 
 sub :: Double -> Gauge -> IO ()
-sub x = flip atomicModifyIORef' f . unGauge
+sub x = modifyAndSample f
   where f v = (v - x, ())
 
 
diff --git a/src/System/Metrics/Prometheus/Metric/Histogram.hs b/src/System/Metrics/Prometheus/Metric/Histogram.hs
--- a/src/System/Metrics/Prometheus/Metric/Histogram.hs
+++ b/src/System/Metrics/Prometheus/Metric/Histogram.hs
@@ -8,13 +8,15 @@
        , new
        , observe
        , sample
+       , observeAndSample
        ) where
 
 
-import           Data.Bool  (bool)
-import           Data.IORef (IORef, atomicModifyIORef', newIORef, readIORef)
-import           Data.Map   (Map)
-import qualified Data.Map   as Map
+import           Control.Monad (void)
+import           Data.Bool     (bool)
+import           Data.IORef    (IORef, atomicModifyIORef', newIORef, readIORef)
+import           Data.Map      (Map)
+import qualified Data.Map      as Map
 
 
 newtype Histogram = Histogram { unHistogram :: IORef HistogramSample }
@@ -40,15 +42,19 @@
     zeroCount = 0
 
 
-observe :: Double -> Histogram -> IO ()
-observe x = flip atomicModifyIORef' update . unHistogram
+observeAndSample :: Double -> Histogram -> IO HistogramSample
+observeAndSample x = flip atomicModifyIORef' update . unHistogram
   where
-    update histData = (hist' histData, ())
+    update histData = (hist' histData, histData)
     hist' histData =
         histData { histBuckets = updateBuckets x $ histBuckets histData
                  , histSum = histSum histData + x
                  , histCount = histCount histData + 1
                  }
+
+
+observe :: Double -> Histogram -> IO ()
+observe x = void . observeAndSample x
 
 
 updateBuckets :: Double -> Buckets -> Buckets