diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 2.4.14
+
+* Add `ToLogStr` instances for the following types: signed integers, unsigned integers, floating-point numbers. These instances all use decimal encodings. [#177](https://github.com/kazu-yamamoto/logger/pull/177)
+
 ## 2.4.11
 
 * Give an explicit definition for (<>) in LogStr's Semigroup instance. [#155](https://github.com/kazu-yamamoto/logger/pull/155)
diff --git a/System/Log/FastLogger/LogStr.hs b/System/Log/FastLogger/LogStr.hs
--- a/System/Log/FastLogger/LogStr.hs
+++ b/System/Log/FastLogger/LogStr.hs
@@ -28,6 +28,8 @@
 import qualified Data.Semigroup as Semi (Semigroup(..))
 #endif
 import Data.String (IsString(..))
+import Data.Int (Int8,Int16,Int32,Int64)
+import Data.Word (Word8,Word16,Word32,Word64)
 import qualified Data.Text as T
 import qualified Data.Text.Encoding as T
 import qualified Data.Text.Lazy as TL
@@ -67,6 +69,9 @@
 instance IsString LogStr where
     fromString = toLogStr . TL.pack
 
+-- | Types that can be converted to a 'LogStr'. Instances for
+-- types from the @text@ library use a UTF-8 encoding. Instances
+-- for numerical types use a decimal encoding.
 class ToLogStr msg where
     toLogStr :: msg -> LogStr
 
@@ -75,7 +80,7 @@
 instance ToLogStr S8.ByteString where
     toLogStr bs = LogStr (BS.length bs) (toBuilder bs)
 instance ToLogStr BL.ByteString where
-    toLogStr = toLogStr . S8.concat . BL.toChunks
+    toLogStr b = LogStr (fromIntegral (BL.length b)) (B.lazyByteString b)
 instance ToLogStr Builder where
     toLogStr x = let b = B.toLazyByteString x in LogStr (fromIntegral (BL.length b)) (B.lazyByteString b)
 instance ToLogStr String where
@@ -84,6 +89,48 @@
     toLogStr = toLogStr . T.encodeUtf8
 instance ToLogStr TL.Text where
     toLogStr = toLogStr . TL.encodeUtf8
+
+-- | @since 2.4.14
+instance ToLogStr Int where
+    toLogStr = toLogStr . B.intDec
+-- | @since 2.4.14
+instance ToLogStr Int8 where
+    toLogStr = toLogStr . B.int8Dec
+-- | @since 2.4.14
+instance ToLogStr Int16 where
+    toLogStr = toLogStr . B.int16Dec
+-- | @since 2.4.14
+instance ToLogStr Int32 where
+    toLogStr = toLogStr . B.int32Dec
+-- | @since 2.4.14
+instance ToLogStr Int64 where
+    toLogStr = toLogStr . B.int64Dec
+
+-- | @since 2.4.14
+instance ToLogStr Word where
+    toLogStr = toLogStr . B.wordDec
+-- | @since 2.4.14
+instance ToLogStr Word8 where
+    toLogStr = toLogStr . B.word8Dec
+-- | @since 2.4.14
+instance ToLogStr Word16 where
+    toLogStr = toLogStr . B.word16Dec
+-- | @since 2.4.14
+instance ToLogStr Word32 where
+    toLogStr = toLogStr . B.word32Dec
+-- | @since 2.4.14
+instance ToLogStr Word64 where
+    toLogStr = toLogStr . B.word64Dec
+
+-- | @since 2.4.14
+instance ToLogStr Integer where
+    toLogStr = toLogStr . B.integerDec
+-- | @since 2.4.14
+instance ToLogStr Float where
+    toLogStr = toLogStr . B.floatDec
+-- | @since 2.4.14
+instance ToLogStr Double where
+    toLogStr = toLogStr . B.doubleDec
 
 instance Show LogStr where
   show = show . T.decodeUtf8 . fromLogStr
diff --git a/fast-logger.cabal b/fast-logger.cabal
--- a/fast-logger.cabal
+++ b/fast-logger.cabal
@@ -1,5 +1,5 @@
 Name:                   fast-logger
-Version:                2.4.13
+Version:                2.4.14
 Author:                 Kazu Yamamoto <kazu@iij.ad.jp>
 Maintainer:             Kazu Yamamoto <kazu@iij.ad.jp>
 License:                BSD3