diff --git a/nix/sources.nix b/nix/sources.nix
index 8a725cb..08002bb 100644
--- a/nix/sources.nix
+++ b/nix/sources.nix
@@ -21,27 +21,13 @@ let
   fetch_git = spec:
     builtins.fetchGit { url = spec.repo; inherit (spec) rev ref; };
 
-  fetch_builtin-tarball = spec:
-    builtins.trace
-      ''
-        WARNING:
-          The niv type "builtin-tarball" will soon be deprecated. You should
-          instead use `builtin = true`.
+  fetch_builtin-tarball = name: throw
+    ''[${name}] The niv type "builtin-tarball" is deprecated. You should instead use `builtin = true`.
+        $ niv modify ${name} -a type=tarball -a builtin=true'';
 
-          $ niv modify <package> -a type=tarball -a builtin=true
-      ''
-      builtins_fetchTarball { inherit (spec) url sha256; };
-
-  fetch_builtin-url = spec:
-    builtins.trace
-      ''
-        WARNING:
-          The niv type "builtin-url" will soon be deprecated. You should
-          instead use `builtin = true`.
-
-          $ niv modify <package> -a type=file -a builtin=true
-      ''
-      (builtins_fetchurl { inherit (spec) url sha256; });
+  fetch_builtin-url = name: throw
+    ''[${name}] The niv type "builtin-url" will soon be deprecated. You should instead use `builtin = true`.
+        $ niv modify ${name} -a type=file -a builtin=true'';
 
   #
   # Various helpers
@@ -74,8 +60,8 @@ let
     else if spec.type == "file" then fetch_file pkgs spec
     else if spec.type == "tarball" then fetch_tarball pkgs spec
     else if spec.type == "git" then fetch_git spec
-    else if spec.type == "builtin-tarball" then fetch_builtin-tarball spec
-    else if spec.type == "builtin-url" then fetch_builtin-url spec
+    else if spec.type == "builtin-tarball" then fetch_builtin-tarball name
+    else if spec.type == "builtin-url" then fetch_builtin-url name
     else
       abort "ERROR: niv spec ${name} has unknown type ${builtins.toJSON spec.type}";
 
diff --git a/src/Niv/Sources.hs b/src/Niv/Sources.hs
index 1386d3a..b26cf46 100644
--- a/src/Niv/Sources.hs
+++ b/src/Niv/Sources.hs
@@ -147,6 +147,7 @@ data SourcesNixVersion
   | V14
   | V15
   | V16
+  | V17
   deriving stock (Bounded, Enum, Eq)
 
 -- | A user friendly version
@@ -168,6 +169,7 @@ sourcesVersionToText = \case
     V14 -> "14"
     V15 -> "15"
     V16 -> "16"
+    V17 -> "17"
 
 latestVersionMD5 :: T.Text
 latestVersionMD5 = sourcesVersionToMD5 maxBound
@@ -196,6 +198,7 @@ sourcesVersionToMD5 = \case
     V14 -> "b470e235e7bcbf106d243fea90b6cfc9"
     V15 -> "dc11af910773ec9b4e505e0f49ebcfd2"
     V16 -> "2d93c52cab8e960e767a79af05ca572a"
+    V17 -> "149b8907f7b08dc1c28164dfa55c7fad"
 
 -- | The MD5 sum of ./nix/sources.nix
 sourcesNixMD5 :: IO T.Text