diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4d30c82..71957bc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 - Raise error for `reindex_status` when Redis not configured
 - Warn when incompatible options used with `body` option
 - Fixed bug where `routing` and `type` options were silently ignored with `body` option
+- Fixed `reindex(async: true)` for non-numeric primary keys in Postgres
 
 ## 2.3.1
 
diff --git a/lib/searchkick/index.rb b/lib/searchkick/index.rb
index 469c692..8a8c012 100644
--- a/lib/searchkick/index.rb
+++ b/lib/searchkick/index.rb
@@ -446,7 +446,13 @@ module Searchkick
         # TODO expire Redis key
         primary_key = scope.primary_key
 
-        starting_id = scope.minimum(primary_key)
+        starting_id =
+          begin
+            scope.minimum(primary_key)
+          rescue ActiveRecord::StatementInvalid
+            false
+          end
+
         if starting_id.nil?
           # no records, do nothing
         elsif starting_id.is_a?(Numeric)
--
libgit2 0.21.0