diff --git a/src/Yam/Logger.hs b/src/Yam/Logger.hs
--- a/src/Yam/Logger.hs
+++ b/src/Yam/Logger.hs
@@ -45,11 +45,11 @@
 
 instance FromProp LogConfig where
   fromProp = LogConfig
-    <$> "buffer-size" .?= bufferSize    def
-    <*> "file"        .?= file          def
-    <*> "max-size"    .?= maxSize       def
-    <*> "max-history" .?= rotateHistory def
-    <*> "level"       .?= level         def
+    <$> "buffer-size" .?: bufferSize
+    <*> "file"        .?: file
+    <*> "max-size"    .?: maxSize
+    <*> "max-history" .?: rotateHistory
+    <*> "level"       .?: level
 
 newLogger :: Text -> IO LogConfig -> IO (LogFunc, IO ())
 newLogger name lc = do
diff --git a/src/Yam/Middleware/Client.hs b/src/Yam/Middleware/Client.hs
--- a/src/Yam/Middleware/Client.hs
+++ b/src/Yam/Middleware/Client.hs
@@ -23,7 +23,7 @@
   def = ClientConfig True
 
 instance FromProp ClientConfig where
-  fromProp = ClientConfig <$> "enabled" .?= enabled def
+  fromProp = ClientConfig <$> "enabled" .?: enabled
 
 {-# NOINLINE managerKey #-}
 managerKey :: L.Key Manager
diff --git a/src/Yam/Middleware/Trace.hs b/src/Yam/Middleware/Trace.hs
--- a/src/Yam/Middleware/Trace.hs
+++ b/src/Yam/Middleware/Trace.hs
@@ -34,8 +34,8 @@
 
 instance FromProp TraceConfig where
   fromProp = TraceConfig
-    <$> "enabled" .?= enabled def
-    <*> "type"    .?= method  def
+    <$> "enabled" .?: enabled
+    <*> "type"    .?: method
 
 instance Default TraceConfig where
   def = TraceConfig True NoTracer
diff --git a/src/Yam/Types/Env.hs b/src/Yam/Types/Env.hs
--- a/src/Yam/Types/Env.hs
+++ b/src/Yam/Types/Env.hs
@@ -22,9 +22,9 @@
 
 instance FromProp AppConfig where
   fromProp = AppConfig
-    <$> "name"           .?= name def
-    <*> "port"           .?= port def
-    <*> "slowloris-size" .?= slowlorisSize def
+    <$> "name"           .?: name
+    <*> "port"           .?: port
+    <*> "slowloris-size" .?: slowlorisSize
 
 data Env = Env
   { attributes    :: Vault
diff --git a/yam.cabal b/yam.cabal
--- a/yam.cabal
+++ b/yam.cabal
@@ -1,6 +1,6 @@
 cabal-version: 1.12
 name: yam
-version: 0.5.15
+version: 0.5.16
 license: BSD3
 license-file: LICENSE
 copyright: (c) 2018 Daniel YU
@@ -116,7 +116,7 @@
                         TypeSynonymInstances ViewPatterns
     ghc-options: -Wall -fno-warn-orphans -fno-warn-missing-signatures
     build-depends:
-        QuickCheck >=2.12.6.1 && <2.13,
+        QuickCheck >=2.12.6.1 && <2.14,
         aeson >=1.4.2.0 && <1.5,
         base >=4.9 && <5,
         base16-bytestring >=0.1.1.6 && <0.2,