diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+0.12.2
+------
+
+- Support servant-0.20 [#69](https://github.com/haskell-servant/servant-multipart/pull/69).
+
 0.12.1
 ------
 
diff --git a/servant-multipart-client.cabal b/servant-multipart-client.cabal
--- a/servant-multipart-client.cabal
+++ b/servant-multipart-client.cabal
@@ -1,5 +1,5 @@
 name:               servant-multipart-client
-version:            0.12.1
+version:            0.12.2
 synopsis:           multipart/form-data (e.g file upload) support for servant
 description:
   This package adds client-side support for file upload to the servant ecosystem.
@@ -14,7 +14,13 @@
 build-type:         Simple
 cabal-version:      >=1.10
 extra-source-files: CHANGELOG.md
-tested-with: GHC ==8.0.2 || ==8.2.2 || ==8.4.4 || ==8.6.5 || ==8.8.4 || ==8.10.4
+tested-with:
+  GHC ==8.6.5
+   || ==8.8.4
+   || ==8.10.7
+   || ==9.0.2
+   || ==9.2.8
+   || ==9.4.7
 
 library
   default-language: Haskell2010
@@ -25,16 +31,23 @@
   build-depends:
       array         >=0.5.1.1  && <0.6
     , base          >=4.9      && <5
-    , bytestring    >=0.10.8.1 && <0.11
-    , text          >=1.2.3.0  && <1.3
+    , bytestring    >=0.10.8.1 && <0.12
+    , text          >=1.2.3.0  && <2.1
     , random        >=0.1.1    && <1.3
 
   -- other dependencies
   build-depends:
       servant-multipart-api == 0.12.*
     , http-media          >=0.7.1.3  && <0.9
-    , servant             >=0.16     && <0.19
-    , servant-client-core >=0.16     && <0.19
+    , servant             >=0.16     && <0.21
+    , servant-client-core >=0.16     && <0.21
+
+  -- servant-0.19 dropped support for GHC-8.4 (latest GHCJS version),
+  -- due to QuantifiedConstraints
+  if impl(ghcjs)
+      build-depends:
+          servant             >=0.16     && <0.19
+        , servant-client-core >=0.16     && <0.19
 
 executable upload
   hs-source-dirs:   exe
diff --git a/src/Servant/Multipart/Client.hs b/src/Servant/Multipart/Client.hs
--- a/src/Servant/Multipart/Client.hs
+++ b/src/Servant/Multipart/Client.hs
@@ -74,7 +74,7 @@
         readHandle hdl = fromActionStep LBS.null (LBS.hGet hdl 4096)
 
 instance MultipartClient Mem where
-    loadFile _ = source . pure
+    loadFile _ = source . pure @[]
 
 -- | Generates a boundary to be used to separate parts of the multipart.
 -- Requires 'IO' because it is randomized.
@@ -132,7 +132,7 @@
     renderInput input = renderPart (lencode . iName $ input)
                                    "text/plain"
                                    ""
-                                   (source . pure . lencode . iValue $ input)
+                                   (source . pure @[] . lencode . iValue $ input)
     inputs' = foldl' (\acc x -> acc `mappend'` renderInput x) mempty' (inputs mp)
     renderFile :: FileData tag -> SourceIO LBS.ByteString
     renderFile file = renderPart (lencode . fdInputName $ file)