diff --git a/llm_anthropic.py b/llm_anthropic.py
index 7a9fadc..e06e418 100644
--- a/llm_anthropic.py
+++ b/llm_anthropic.py
@@ -183,6 +183,11 @@ def __init__(
         if supports_pdf:
             self.attachment_types.add("application/pdf")
 
+    def prefill_text(self, prompt):
+        if prompt.options.prefill and not prompt.options.hide_prefill:
+            return prompt.options.prefill
+        return ""
+
     def build_messages(self, prompt, conversation) -> List[dict]:
         messages = []
         if conversation:
@@ -285,10 +290,11 @@ class ClaudeMessages(_Shared, llm.Model):
     def execute(self, prompt, stream, response, conversation):
         client = Anthropic(api_key=self.get_key())
         kwargs = self.build_kwargs(prompt, conversation)
+        prefill_text = self.prefill_text(prompt)
         if stream:
             with client.messages.stream(**kwargs) as stream:
-                if prompt.options.prefill and not prompt.options.hide_prefill:
-                    yield prompt.options.prefill
+                if prefill_text:
+                    yield prefill_text
                 for text in stream.text_stream:
                     yield text
                 # This records usage and other data:
@@ -296,9 +302,7 @@ def execute(self, prompt, stream, response, conversation):
         else:
             completion = client.messages.create(**kwargs)
             text = completion.content[0].text
-            if prompt.options.prefill and not prompt.options.hide_prefill:
-                text = prompt.options.prefill + text
-            yield text
+            yield prefill_text + text
             response.response_json = completion.model_dump()
         self.set_usage(response)
 
@@ -312,19 +316,18 @@ class AsyncClaudeMessages(_Shared, llm.AsyncModel):
     async def execute(self, prompt, stream, response, conversation):
         client = AsyncAnthropic(api_key=self.get_key())
         kwargs = self.build_kwargs(prompt, conversation)
+        prefill_text = self.prefill_text(prompt)
         if stream:
             async with client.messages.stream(**kwargs) as stream_obj:
-                if prompt.options.prefill and not prompt.options.hide_prefill:
-                    yield prompt.options.prefill
+                if prefill_text:
+                    yield prefill_text
                 async for text in stream_obj.text_stream:
                     yield text
             response.response_json = (await stream_obj.get_final_message()).model_dump()
         else:
             completion = await client.messages.create(**kwargs)
             text = completion.content[0].text
-            if prompt.options.prefill and not prompt.options.hide_prefill:
-                text = prompt.options.prefill + text
-            yield text
+            yield prefill_text + text
             response.response_json = completion.model_dump()
         self.set_usage(response)