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..438f01994 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
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