diff --git a/examples/Simple.hs b/examples/Simple.hs
--- a/examples/Simple.hs
+++ b/examples/Simple.hs
@@ -4,17 +4,18 @@
 module Simple where
 
 import Control.Monad
-import Data.Monoid
 import System.Process
 
 import Zenity
 
+config = def {debug = True}
+
 -- Ask for a name and display a greeting
 greeting = do
   Just name <-
-    zenity def {title = Just "Name entry"} $
+    zenity config {title = Just "Name entry"} $
     Entry $ def {text = Just "What's your name?"}
-  zenity def $ Info def {text = Just $ "Greetings, " <> name <> "!"}
+  zenity config $ Info def {text = Just $ "Greetings, " <> name <> "!"}
 
 data SystemCommand
   = Ls
@@ -27,7 +28,7 @@
 -- `keyedList` allows associating each option with a value of some type. We can
 -- then scrutinize the result by matching on the associated values.
 systemOperation = do
-  op <- keyedList def radio def
+  op <- keyedList config radio def
     "Select a command"
     [ (Ls, "List files")
     , (Pwd, "Show current directory")
diff --git a/hzenity.cabal b/hzenity.cabal
--- a/hzenity.cabal
+++ b/hzenity.cabal
@@ -1,5 +1,5 @@
 name:                hzenity
-version:             0.3
+version:             0.4
 synopsis:            Haskell interface to Zenity dialogs
 description:         This is a Haskell wrapper around the
                      <https://en.wikipedia.org/wiki/Zenity Zenity> dialog
@@ -27,12 +27,14 @@
 library
   exposed-modules:     Zenity
   build-depends:       base <5,
-                       containers,
-                       data-default,
-                       process,
-                       process-extras,
-                       text,
-                       time
+                       containers < 0.7,
+                       data-default < 0.8,
+                       process < 1.7,
+                       process-extras < 0.8,
+                       text < 1.3,
+                       time < 1.10
+                         -- `time-1.10` is currently incompatible with `process`
+                         -- so I can't test it.
   hs-source-dirs:      src
   default-language:    Haskell2010
   default-extensions:  DeriveFunctor
diff --git a/src/Zenity.hs b/src/Zenity.hs
--- a/src/Zenity.hs
+++ b/src/Zenity.hs
@@ -98,6 +98,7 @@
   , width :: Maybe Int -- ^ Dialog width
   , height :: Maybe Int -- ^ Dialog height
   , timeout :: Maybe Int -- ^ Dialog timeout in seconds
+  , debug :: Bool -- ^ Print the system call to Zenity with flags
   }
 
 instance Default Config where
@@ -107,6 +108,7 @@
     , width = Nothing
     , height = Nothing
     , timeout = Nothing
+    , debug = False
     }
 
 data CmdFlag where
@@ -387,8 +389,7 @@
   -> [String] -- ^ Additional command-line flags
   -> IO Text
 callZenity cfg flags = do
-  -- Set to `True` for logging:
-  when False $ putStrLn $ showCommandForUser "zenity" flags'
+  when (debug cfg) $ putStrLn $ showCommandForUser "zenity" flags'
   (\(_, o, _) -> o) <$> Text.readProcessWithExitCode "zenity" flags' ""
   where
     flags' = configFlags cfg ++ flags