diff --git a/query/llm_interface.py b/query/llm_interface.py
index 2f98e0e..ed18090 100644
--- a/query/llm_interface.py
+++ b/query/llm_interface.py
@@ -127,7 +127,28 @@ class LLMInterface:
         """
         try:
             params = self._get_completion_params()
-            params['messages'] = messages
+            
+            # Special handling for Gemini models
+            if "gemini" in params.get('model', '').lower():
+                # Format messages for Gemini models
+                formatted_messages = []
+                for msg in messages:
+                    role = msg['role']
+                    # Gemini uses 'user' and 'model' roles (not 'assistant')
+                    if role == 'assistant':
+                        role = 'model'
+                    # For system messages, convert to user messages with a prefix
+                    if role == 'system':
+                        formatted_messages.append({
+                            "role": "user", 
+                            "content": f"System instruction: {msg['content']}"
+                        })
+                    else:
+                        formatted_messages.append({"role": role, "content": msg['content']})
+                params['messages'] = formatted_messages
+            else:
+                params['messages'] = messages
+                
             params['stream'] = stream
             
             response = completion(**params)
diff --git a/report/report_synthesis.py b/report/report_synthesis.py
index 5f4bcec..ca0eacd 100644
--- a/report/report_synthesis.py
+++ b/report/report_synthesis.py
@@ -123,7 +123,28 @@ class ReportSynthesizer:
         """
         try:
             params = self._get_completion_params()
-            params['messages'] = messages
+            
+            # Special handling for Gemini models
+            if "gemini" in params.get('model', '').lower():
+                # Format messages for Gemini models
+                formatted_messages = []
+                for msg in messages:
+                    role = msg['role']
+                    # Gemini uses 'user' and 'model' roles (not 'assistant')
+                    if role == 'assistant':
+                        role = 'model'
+                    # For system messages, convert to user messages with a prefix
+                    if role == 'system':
+                        formatted_messages.append({
+                            "role": "user", 
+                            "content": f"System instruction: {msg['content']}"
+                        })
+                    else:
+                        formatted_messages.append({"role": role, "content": msg['content']})
+                params['messages'] = formatted_messages
+            else:
+                params['messages'] = messages
+                
             params['stream'] = stream
             
             logger.info(f"Generating completion with model: {params.get('model')}")