diff --git a/.tool-versions b/.tool-versions
index f7487cb..e223891 100644
--- a/.tool-versions
+++ b/.tool-versions
@@ -1,2 +1,2 @@
-elixir 1.19.5-otp-28
-erlang 28.4.1
+elixir 1.20.4-otp-29
+erlang 29.1.2
diff --git a/lib/live_sync.ex b/lib/live_sync.ex
index a389d98..dc31b54 100644
--- a/lib/live_sync.ex
+++ b/lib/live_sync.ex
@@ -172,12 +172,8 @@ defmodule LiveSync do
     quote do
       on_mount({LiveSync, unquote(opts)})
 
-      def sync(key, value, socket), do: assign(socket, key, value)
-      def sync(key, value, _operations, socket), do: sync(key, value, socket)
-
+      # the fallbacks go last so they catch whatever the LiveView's own clauses don't
       @before_compile {LiveSync, :add_sync_fallback}
-
-      defoverridable sync: 3, sync: 4
     end
   end
 
@@ -205,7 +201,7 @@ defmodule LiveSync do
   end
 
   def opts(module) do
-    LiveSync.Watch.impl_for(struct(module)).opts()
+    LiveSync.Watch.impl_for!(struct(module)).opts()
   end
 
   @doc """
@@ -228,7 +224,6 @@ defmodule LiveSync do
       2
   """
   def subscription_key(struct) do
-    impl = LiveSync.Watch.impl_for(struct)
-    impl.subscription_key(struct)
+    LiveSync.Watch.impl_for!(struct).subscription_key(struct)
   end
 end
diff --git a/mix.exs b/mix.exs
index 1af102e..901d72e 100644
--- a/mix.exs
+++ b/mix.exs
@@ -4,7 +4,7 @@ defmodule LiveSync.MixProject do
   def project do
     [
       app: :live_sync,
-      version: "0.1.12",
+      version: "0.1.13",
       elixir: "~> 1.17",
       elixirc_paths: elixirc_paths(Mix.env()),
       start_permanent: Mix.env() == :prod,