diff --git a/src/Hpack/Config.hs b/src/Hpack/Config.hs
index cb84f71..5566b8c 100644
--- a/src/Hpack/Config.hs
+++ b/src/Hpack/Config.hs
@@ -101,3 +101,9 @@ githubBaseUrl = "https://github.com/"
 
-genericParseJSON_ :: forall a. (Generic a, GFromJSON (Rep a), HasTypeName a) => Value -> Parser a
+#if MIN_VERSION_aeson(1,0,0)
+#    define AESON_ARITY Zero
+#else
+#    define AESON_ARITY
+#endif
+
+genericParseJSON_ :: forall a. (Generic a, GFromJSON AESON_ARITY (Rep a), HasTypeName a) => Value -> Parser a
 genericParseJSON_ = genericParseJSON defaultOptions {fieldLabelModifier = hyphenize name}
diff --git a/test/Hpack/ConfigSpec.hs b/test/Hpack/ConfigSpec.hs
index 320ba9a..d13d932 100644
--- a/test/Hpack/ConfigSpec.hs
+++ b/test/Hpack/ConfigSpec.hs
@@ -971,3 +971,3 @@ spec = do
             |]
-          readPackageConfig file `shouldReturn` Left (file ++ ": Error in $.executables.foo: failed to parse field executables: The key \"main\" was not found")
+          readPackageConfig file `shouldReturn` Left (file ++ ": Error in $.executables.foo: key \"main\" not present")