diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 000000000..1bf30d848
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,8 @@
+
+## 2.3.0
+
+*   Change the `observeAndSample` function from the
+    `System.Metrics.Prometheus.Metric.Histogram` module to return the value of
+    the sample that was just added, instead of the previous sample.
+    This change matches similar functions for `Counter`s and `Gauge`s.
+    [#51](https://github.com/bitnomial/prometheus/pull/51)
diff --git a/prometheus.cabal b/prometheus.cabal
index fb91b64fb..1feb401c1 100644
--- a/prometheus.cabal
+++ b/prometheus.cabal
@@ -1,5 +1,5 @@
 name:                prometheus
-version:             2.2.4
+version:             2.3.0
 synopsis:            Prometheus Haskell Client
 homepage:            http://github.com/bitnomial/prometheus
 bug-reports:         http://github.com/bitnomial/prometheus/issues
@@ -7,7 +7,7 @@ license:             BSD3
 license-file:        LICENSE
 author:              Luke Hoersten
 maintainer:          luke@bitnomial.com, opensource@bitnomial.com
-copyright:           Bitnomial, Inc. (c) 2016-2019
+copyright:           Bitnomial, Inc. (c) 2016-2023
 category:            Metrics, Monitoring, Web, System
 build-type:          Simple
 cabal-version:       >=1.10
diff --git a/src/System/Metrics/Prometheus/Metric/Counter.hs b/src/System/Metrics/Prometheus/Metric/Counter.hs
index f76a3edcd..70d8148f4 100644
--- a/src/System/Metrics/Prometheus/Metric/Counter.hs
+++ b/src/System/Metrics/Prometheus/Metric/Counter.hs
@@ -15,7 +15,7 @@ import Data.Atomics.Counter (AtomicCounter, incrCounter, newCounter, writeCounte
 
 
 newtype Counter = Counter {unCounter :: AtomicCounter}
-newtype CounterSample = CounterSample {unCounterSample :: Int}
+newtype CounterSample = CounterSample {unCounterSample :: Int} deriving Show
 
 
 new :: IO Counter
diff --git a/src/System/Metrics/Prometheus/Metric/Gauge.hs b/src/System/Metrics/Prometheus/Metric/Gauge.hs
index 76610e221..3c0852e2c 100644
--- a/src/System/Metrics/Prometheus/Metric/Gauge.hs
+++ b/src/System/Metrics/Prometheus/Metric/Gauge.hs
@@ -16,7 +16,7 @@ import Data.IORef (IORef, atomicModifyIORef', newIORef)
 
 
 newtype Gauge = Gauge {unGauge :: IORef Double}
-newtype GaugeSample = GaugeSample {unGaugeSample :: Double}
+newtype GaugeSample = GaugeSample {unGaugeSample :: Double} deriving Show
 
 
 new :: IO Gauge
diff --git a/src/System/Metrics/Prometheus/Metric/Histogram.hs b/src/System/Metrics/Prometheus/Metric/Histogram.hs
index fbd26528a..39a49c26a 100644
--- a/src/System/Metrics/Prometheus/Metric/Histogram.hs
+++ b/src/System/Metrics/Prometheus/Metric/Histogram.hs
@@ -36,6 +36,7 @@ data HistogramSample = HistogramSample
     , histSum :: !Double
     , histCount :: !Int
     }
+    deriving Show
 
 
 new :: [UpperBound] -> IO Histogram
@@ -49,7 +50,7 @@ new buckets = Histogram <$> newIORef empty
 observeAndSample :: Double -> Histogram -> IO HistogramSample
 observeAndSample x = flip atomicModifyIORef' update . unHistogram
   where
-    update histData = (hist' histData, histData)
+    update histData = (hist' histData, hist' histData)
     hist' histData =
         histData
             { histBuckets = updateBuckets x $ histBuckets histData
diff --git a/src/System/Metrics/Prometheus/Metric/Summary.hs b/src/System/Metrics/Prometheus/Metric/Summary.hs
index 98f2498ef..feff1b230 100644
--- a/src/System/Metrics/Prometheus/Metric/Summary.hs
+++ b/src/System/Metrics/Prometheus/Metric/Summary.hs
@@ -8,3 +8,4 @@ data SummarySample = SummarySample
     , sumSum :: !Int
     , sumCount :: !Int
     }
+    deriving Show