diff --git a/include-env.cabal b/include-env.cabal
--- a/include-env.cabal
+++ b/include-env.cabal
@@ -1,5 +1,5 @@
 name:                include-env
-version:             0.2.0.0
+version:             0.3.0.0
 synopsis:            Include the value of an environment variable at compile time
 description:         Embed secrets (e.g. API keys) inside production artifacts at compile time.
 homepage:            https://github.com/unfoldml/include-env
diff --git a/src/IncludeEnv/TH.hs b/src/IncludeEnv/TH.hs
--- a/src/IncludeEnv/TH.hs
+++ b/src/IncludeEnv/TH.hs
@@ -25,7 +25,7 @@
 
 -- template-haskell
 import Language.Haskell.TH (runIO, runQ)
-import Language.Haskell.TH.Syntax (Q, Exp(..), Dec(..), Pat(..), Name, mkName, Body(..), Lit(..))
+import Language.Haskell.TH.Syntax (Q, Exp(..), Dec(..), Pat(..), Name, mkName, Body(..), Lit(..), reportWarning)
 import Language.Haskell.TH.Lib (valD)
 
 
@@ -60,7 +60,7 @@
   case mstr of
     Just str -> decl varname str
     Nothing -> do
-      runIO $ putStrLn $ unwords ["*** WARNING : Cannot find variable", e, "in the environment."]
+      reportWarning $ unwords ["*** WARNING : Cannot find variable", e, "in the environment."]
       decl varname ""
     where
       decl :: String -> String -> Q [Dec]
@@ -68,5 +68,4 @@
         dq = ValD qpat qbody []
         qpat = VarP (mkName n)
         qbody = NormalB (LitE (StringL x))
-