diff --git a/.changeset/happy-buttons-end.md b/.changeset/happy-buttons-end.md
new file mode 100644
index 0000000000..0bf7f9f306
--- /dev/null
+++ b/.changeset/happy-buttons-end.md
@@ -0,0 +1,5 @@
+---
+"@core/electric": patch
+---
+
+Rewrite the type-validating part of `electify` function to expand allowed types when Electric instance is upgraded
diff --git a/components/electric/lib/electric/postgres/extension.ex b/components/electric/lib/electric/postgres/extension.ex
index 3d8db7c217..ddfa904cba 100644
--- a/components/electric/lib/electric/postgres/extension.ex
+++ b/components/electric/lib/electric/postgres/extension.ex
@@ -3,7 +3,7 @@ defmodule Electric.Postgres.Extension do
   Manages our pseudo-extension code
   """
 
-  alias Electric.Postgres.{Extension.Migration, Schema, Schema.Proto}
+  alias Electric.Postgres.{Schema, Schema.Proto, Extension.Functions, Extension.Migration}
   alias Electric.Utils
 
   require Logger
@@ -227,6 +227,16 @@ defmodule Electric.Postgres.Extension do
     end
   end
 
+  @spec define_functions(conn) :: :ok
+  def define_functions(conn) do
+    Enum.each(Functions.list(), fn {name, sql} ->
+      case :epgsql.squery(conn, sql) do
+        {:ok, [], []} -> :ok
+        error -> raise "Failed to define function '#{name}' with error: #{inspect(error)}"
+      end
+    end)
+  end
+
   @spec migrations() :: [module(), ...]
   def migrations do
     alias Electric.Postgres.Extension.Migrations
@@ -266,6 +276,13 @@ defmodule Electric.Postgres.Extension do
       create_migration_table(txconn)
 
       with_migration_lock(txconn, fn ->
+        # NOTE(alco): This is currently called BEFORE running any internal migrations because we're only defining the
+        # type-checking function that the later defined `electrify()` function depends on.
+        #
+        # Once we move all function definitions out of migrations, we should call this AFTER all internal migrations
+        # have been applied.
+        define_functions(txconn)
+
         existing_migrations = existing_migrations(txconn)
 
         versions =
diff --git a/components/electric/lib/electric/postgres/extension/functions.ex b/components/electric/lib/electric/postgres/extension/functions.ex
new file mode 100644
index 0000000000..48beaf1e98
--- /dev/null
+++ b/components/electric/lib/electric/postgres/extension/functions.ex
@@ -0,0 +1,26 @@
+defmodule Electric.Postgres.Extension.Functions do
+  require EEx
+
+  sql_files =
+    "functions/*.sql.eex"
+    |> Path.expand(__DIR__)
+    |> Path.wildcard()
+
+  for path <- sql_files, do: @external_resource(path)
+
+  @function_defs Map.new(sql_files, fn path ->
+                   {Path.basename(path, ".sql.eex"), {Path.basename(path), File.read!(path)}}
+                 end)
+
+  @doc """
+  Get a list of SQL statements that create various internal SQL functions in the `electric` schema.
+
+  Every function in the list is defined as `CREATE OR REPLACE FUNCTION`.
+  """
+  def list do
+    for {name, args} <- [{"validate_table_column_types", []}] do
+      {filename, sql} = @function_defs[name]
+      {name, EEx.eval_string(sql, args, file: filename)}
+    end
+  end
+end
diff --git a/components/electric/lib/electric/postgres/extension/functions/validate_table_column_types.sql.eex b/components/electric/lib/electric/postgres/extension/functions/validate_table_column_types.sql.eex
new file mode 100644
index 0000000000..fdb9ee9cdc
--- /dev/null
+++ b/components/electric/lib/electric/postgres/extension/functions/validate_table_column_types.sql.eex
@@ -0,0 +1,47 @@
+<%
+  valid_column_types =
+    ~w[
+      bool
+      date
+      float8
+      int2 int4
+      text
+      time
+      timestamp timestamptz
+      uuid
+      varchar
+    ]a
+    |> Enum.map(&"'#{&1}'")
+    |> Enum.join(",")
+%>
+
+CREATE OR REPLACE FUNCTION electric.__validate_table_column_types(table_name text)
+RETURNS VOID AS $function$
+DECLARE
+    _col_name text;
+    _col_type text;
+    _col_typmod int;
+    _col_type_pretty text;
+    _invalid_cols text[];
+BEGIN
+    FOR _col_name, _col_type, _col_typmod, _col_type_pretty IN
+        SELECT attname, typname, atttypmod, format_type(atttypid, atttypmod)
+            FROM pg_attribute
+            JOIN pg_type on atttypid = pg_type.oid
+            WHERE attrelid = table_name::regclass AND attnum > 0 AND NOT attisdropped
+            ORDER BY attnum
+    LOOP
+        IF _col_type NOT IN (<%= valid_column_types %>)
+           -- We only support unsized varchar type
+           OR ('varchar' IN (<%= valid_column_types %>) AND _col_type = 'varchar' AND _col_typmod <> -1)
+        THEN
+            _invalid_cols = array_append(_invalid_cols, format('"%s" %s', _col_name, _col_type_pretty));
+        END IF;
+    END LOOP;
+
+    IF _invalid_cols IS NOT NULL THEN
+        RAISE EXCEPTION E'Cannot electrify "%" because some of its columns have types not supported by Electric:\n  %',
+                        table_name, array_to_string(_invalid_cols, E'\n  ');
+    END IF;
+END;
+$function$ LANGUAGE PLPGSQL;
diff --git a/components/electric/lib/electric/postgres/extension/migrations/20230605141256_electrify_function.ex b/components/electric/lib/electric/postgres/extension/migrations/20230605141256_electrify_function.ex
index e3c57bbef3..418fc14fb3 100644
--- a/components/electric/lib/electric/postgres/extension/migrations/20230605141256_electrify_function.ex
+++ b/components/electric/lib/electric/postgres/extension/migrations/20230605141256_electrify_function.ex
@@ -20,19 +20,13 @@ defmodule Electric.Postgres.Extension.Migrations.Migration_20230605141256_Electr
     event_triggers = Extension.event_triggers()
     event_trigger_tags = ["'ALTER TABLE'", "'DROP TABLE'", "'DROP INDEX'", "'DROP VIEW'"]
 
-    supported_types_sql =
-      Electric.Satellite.Serialization.supported_pg_types()
-      |> Enum.map(&"'#{&1}'")
-      |> Enum.join(",")
-
     electrify_function =
       electrify_function_sql(
         schema,
         electrified_tracking_table,
         Extension.electrified_index_table(),
         publication,
-        Extension.add_table_to_publication_sql("%I.%I"),
-        supported_types_sql
+        Extension.add_table_to_publication_sql("%I.%I")
       )
 
     [
@@ -77,7 +71,6 @@ defmodule Electric.Postgres.Extension.Migrations.Migration_20230605141256_Electr
     :electrified_tracking_table,
     :electrified_index_table,
     :publication_name,
-    :publication_sql,
-    :valid_column_types
+    :publication_sql
   ])
 end
diff --git a/components/electric/lib/electric/postgres/extension/migrations/20230605141256_electrify_function/electrify.sql.eex b/components/electric/lib/electric/postgres/extension/migrations/20230605141256_electrify_function/electrify.sql.eex
index aea7a404dc..8069f10369 100644
--- a/components/electric/lib/electric/postgres/extension/migrations/20230605141256_electrify_function/electrify.sql.eex
+++ b/components/electric/lib/electric/postgres/extension/migrations/20230605141256_electrify_function/electrify.sql.eex
@@ -91,39 +91,6 @@ $function$ LANGUAGE PLPGSQL STABLE;
 
 -------------------------------------------------
 
-CREATE OR REPLACE FUNCTION <%= schema %>.__validate_table_column_types(table_name text)
-RETURNS VOID AS $function$
-DECLARE
-    _col_name text;
-    _col_type text;
-    _col_typmod int;
-    _col_type_pretty text;
-    _invalid_cols text[];
-BEGIN
-    FOR _col_name, _col_type, _col_typmod, _col_type_pretty IN
-        SELECT attname, typname, atttypmod, format_type(atttypid, atttypmod)
-            FROM pg_attribute
-            JOIN pg_type on atttypid = pg_type.oid
-            WHERE attrelid = table_name::regclass AND attnum > 0 AND NOT attisdropped
-            ORDER BY attnum
-    LOOP
-        IF _col_type NOT IN (<%= valid_column_types %>)
-           -- We only support unsized varchar type
-           OR ('varchar' IN (<%= valid_column_types %>) AND _col_type = 'varchar' AND _col_typmod <> -1)
-        THEN
-            _invalid_cols = array_append(_invalid_cols, format('"%s" %s', _col_name, _col_type_pretty));
-        END IF;
-    END LOOP;
-
-    IF _invalid_cols IS NOT NULL THEN
-        RAISE EXCEPTION E'Cannot electrify "%" because some of its columns have types not supported by Electric:\n  %',
-                        table_name, array_to_string(_invalid_cols, E'\n  ');
-    END IF;
-END;
-$function$ LANGUAGE PLPGSQL;
-
--------------------------------------------------
-
 CREATE OR REPLACE PROCEDURE <%= schema %>.electrify(
     name1 text,
     name2 text DEFAULT NULL
diff --git a/components/electric/lib/electric/satellite/serialization.ex b/components/electric/lib/electric/satellite/serialization.ex
index 848ecb1cc6..0962891cd8 100644
--- a/components/electric/lib/electric/satellite/serialization.ex
+++ b/components/electric/lib/electric/satellite/serialization.ex
@@ -21,21 +21,6 @@ defmodule Electric.Satellite.Serialization do
   @type relation_mapping() ::
           %{Changes.relation() => {PB.relation_id(), [Replication.Column.name()]}}
 
-  @spec supported_pg_types :: [atom]
-  def supported_pg_types do
-    ~w[
-      bool
-      date
-      float8
-      int2 int4
-      text
-      time
-      timestamp timestamptz
-      uuid
-      varchar
-    ]a
-  end
-
   @doc """
   Serialize from internal format to Satellite PB format
   """
diff --git a/docs/usage/data-modelling/types.md b/docs/usage/data-modelling/types.md
index 3eccb0adcf..c69e1e3f58 100644
--- a/docs/usage/data-modelling/types.md
+++ b/docs/usage/data-modelling/types.md
@@ -43,7 +43,7 @@ You are responsible for ensuring the uniqueness of your primary keys. If you som
 - `boolean`
 - `uuid`
 
-The authoritative list of supported data types is maintained in the [`supported_pg_types/0` function](https://github.com/search?q=repo%3Aelectric-sql%2Felectric+symbol%3Asupported_pg_types&type=code).
+The authoritative list of supported data types is maintained in the [`validate_table_column_types.sql.eex` file](https://github.com/electric-sql/electric/blob/main/components/electric/lib/electric/postgres/extension/functions/validate_table_column_types.sql.eex).
 
 :::caution Work in progress
 We are actively working on building out data type support. If you need a type we don't yet support, please [let us know on Discord](https://discord.electric-sql.com).