diff --git a/Changes.md b/Changes.md
index 9f892e79..c5852a5a 100644
--- a/Changes.md
+++ b/Changes.md
@@ -5,6 +5,7 @@
 HEAD
 ---------
 
+- Strict argument checking now runs after client-side middleware [#5246]
 - Fix page events with live polling [#5184]
 - Many under-the-hood changes to remove all usage of the term "worker"
   from the Sidekiq codebase and APIs. This mostly involved RDoc and local
diff --git a/lib/sidekiq/client.rb b/lib/sidekiq/client.rb
index 4b137548..1dced454 100644
--- a/lib/sidekiq/client.rb
+++ b/lib/sidekiq/client.rb
@@ -75,6 +75,7 @@ module Sidekiq
         normed
       end
       if payload
+        verify_json(payload)
         raw_push([payload])
         payload["jid"]
       end
@@ -110,6 +111,7 @@ module Sidekiq
         copy = normed.merge("args" => job_args, "jid" => SecureRandom.hex(12))
         copy["at"] = (at.is_a?(Array) ? at[index] : at) if at
         result = middleware.invoke(copy["class"], copy, copy["queue"], @redis_pool) do
+          verify_json(copy)
           copy
         end
         result || nil
diff --git a/lib/sidekiq/job_util.rb b/lib/sidekiq/job_util.rb
index 3e520acc..721bade6 100644
--- a/lib/sidekiq/job_util.rb
+++ b/lib/sidekiq/job_util.rb
@@ -12,7 +12,9 @@ module Sidekiq
       raise(ArgumentError, "Job class must be either a Class or String representation of the class name: `#{item}`") unless item["class"].is_a?(Class) || item["class"].is_a?(String)
       raise(ArgumentError, "Job 'at' must be a Numeric timestamp: `#{item}`") if item.key?("at") && !item["at"].is_a?(Numeric)
       raise(ArgumentError, "Job tags must be an Array: `#{item}`") if item["tags"] && !item["tags"].is_a?(Array)
+    end
 
+    def verify_json(item)
       job_class = item["wrapped"] || item["class"]
       if Sidekiq.options[:on_complex_arguments] == :raise
         msg = <<~EOM