diff --git a/lib/completions/prompt.rb b/lib/completions/prompt.rb
index 95ef3fe8..e5a2e2e8 100644
--- a/lib/completions/prompt.rb
+++ b/lib/completions/prompt.rb
@@ -22,6 +22,10 @@ module DiscourseAi
         @messages.concat(messages)
 
         @messages.each { |message| validate_message(message) }
+        @messages.each do |message|
+          message[:id] = clean_username(message[:id]) if message[:type] == :user &&
+            message[:id].present?
+        end
         @messages.each_cons(2) { |last_turn, new_turn| validate_turn(last_turn, new_turn) }
 
         @tools = tools
diff --git a/spec/lib/completions/prompt_spec.rb b/spec/lib/completions/prompt_spec.rb
index 2fa150e5..7ef4620e 100644
--- a/spec/lib/completions/prompt_spec.rb
+++ b/spec/lib/completions/prompt_spec.rb
@@ -21,6 +21,18 @@ RSpec.describe DiscourseAi::Completions::Prompt do
       bad_messages3 = [{ content: "some content associated to no one" }]
       expect { described_class.new("a bot", messages: bad_messages3) }.to raise_error(ArgumentError)
     end
+
+    it "cleans unicode usernames" do
+      unicode_username = "罗马罗马"
+
+      prompt =
+        described_class.new(
+          "a bot",
+          messages: [{ type: :user, content: user_msg, id: unicode_username }],
+        )
+
+      expect(prompt.messages.last[:id]).to eq("____")
+    end
   end
 
   describe "#push" do
@@ -62,5 +74,14 @@ RSpec.describe DiscourseAi::Completions::Prompt do
       expect(system_message[:content]).to eq(user_msg)
       expect(system_message[:id]).to eq(username)
     end
+
+    it "cleans unicode usernames" do
+      unicode_username = "罗马罗马"
+      prompt.push(type: :user, content: user_msg, id: unicode_username)
+
+      user_message = prompt.messages.last
+
+      expect(user_message[:id]).to eq("____")
+    end
   end
 end