diff --git a/modem/arq_session_irs.py b/modem/arq_session_irs.py
index defa65f5..0988c787 100644
--- a/modem/arq_session_irs.py
+++ b/modem/arq_session_irs.py
@@ -120,7 +120,7 @@ class ARQSessionIRS(arq_session.ARQSession):
 
         # Enable mode based on speed_level
         self.modem.demodulator.MODE_DICT[
-            self.SPEED_LEVEL_DICT[self.speed_level]["mode"]
+            self.SPEED_LEVEL_DICT[self.speed_level]["mode"].value
         ]["decode"] = True
         self.log(f"Modem set to speed level {speed_level}")
 
diff --git a/modem/demodulator.py b/modem/demodulator.py
index 9a1ef602..4b87d951 100644
--- a/modem/demodulator.py
+++ b/modem/demodulator.py
@@ -22,7 +22,7 @@ class Demodulator():
             'audio_buffer': None,
             'nin': None,
             'instance': None,
-            'state_buffer': None,
+            'state_buffer': [],
             'name': mode.name.upper(),
             'decoding_thread': None
         }