diff --git a/CHANGELOG.md b/CHANGELOG.md
index af91cb43d..f0f9cea39 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed an issue with the `TavusVideoService` where an error was thrown due to
   missing transcription callbacks.
 
+- Fixed an issue in `SpeechmaticsSTTService` where the `user_id` was set to
+  `None` when diarization is not enabled.
+
 ### Performance
 
 - Fixed an issue in `TaskObserver` (a proxy to all observers) that was degrading
diff --git a/examples/foundational/13h-speechmatics-transcription.py b/examples/foundational/13h-speechmatics-transcription.py
index 173d0641c..92c8d4f91 100644
--- a/examples/foundational/13h-speechmatics-transcription.py
+++ b/examples/foundational/13h-speechmatics-transcription.py
@@ -49,7 +49,7 @@ async def run_bot(transport: BaseTransport):
     This example will use diarization within our STT service and output the words spoken by
     each individual speaker and wrap them with XML tags.
 
-    If you do not wish to use diarization, then set the `enable_speaker_diarization` parameter
+    If you do not wish to use diarization, then set the `enable_diarization` parameter
     to `False` or omit it altogether. The `text_format` will only be used if diarization is enabled.
 
     By default, this example will use our ENHANCED operating point, which is optimized for
diff --git a/src/pipecat/services/speechmatics/stt.py b/src/pipecat/services/speechmatics/stt.py
index d6c947d38..6859306d3 100644
--- a/src/pipecat/services/speechmatics/stt.py
+++ b/src/pipecat/services/speechmatics/stt.py
@@ -191,7 +191,7 @@ class SpeakerFragments:
             passive_format = active_format
         return {
             "text": self._format_text(active_format if self.is_active else passive_format),
-            "user_id": self.speaker_id,
+            "user_id": self.speaker_id or "",
             "timestamp": self.timestamp,
             "language": self.language,
             "result": [frag.result for frag in self.fragments],