diff --git a/servant-purescript.cabal b/servant-purescript.cabal
--- a/servant-purescript.cabal
+++ b/servant-purescript.cabal
@@ -1,5 +1,5 @@
 name:                servant-purescript
-version:             0.3.1.3
+version:             0.3.1.4
 synopsis:            Generate PureScript accessor functions for you servant API
 description:         Please see README.md
 homepage:            https://github.com/eskimor/servant-purescript#readme
diff --git a/src/Servant/PureScript/CodeGen.hs b/src/Servant/PureScript/CodeGen.hs
--- a/src/Servant/PureScript/CodeGen.hs
+++ b/src/Servant/PureScript/CodeGen.hs
@@ -170,7 +170,7 @@
 genBuildHeader (ReplaceHeaderArg _ _) = error "ReplaceHeaderArg - not yet implemented!"
 
 reqsToImportLines :: [Req PSType] -> ImportLines
-reqsToImportLines = typesToImportLines Map.empty . concatMap reqToPSTypes
+reqsToImportLines = typesToImportLines Map.empty . Set.fromList . concatMap reqToPSTypes
 
 reqToPSTypes :: Req PSType -> [PSType]
 reqToPSTypes req = map _pType (reqToParams req) ++ maybeToList (req ^. reqReturnType)