diff --git a/backend/danswer/prompts/prompt_utils.py b/backend/danswer/prompts/prompt_utils.py
index cd59e97061f..5e1a3e298fb 100644
--- a/backend/danswer/prompts/prompt_utils.py
+++ b/backend/danswer/prompts/prompt_utils.py
@@ -13,6 +13,10 @@
 from danswer.prompts.chat_prompts import CITATION_REMINDER
 from danswer.prompts.constants import CODE_BLOCK_PAT
 from danswer.search.models import InferenceChunk
+from danswer.utils.logger import setup_logger
+
+
+logger = setup_logger()
 
 
 MOST_BASIC_PROMPT = "You are a helpful AI assistant."
@@ -136,14 +140,23 @@ def find_last_index(lst: list[int], max_prompt_tokens: int) -> int:
     before the list exceeds the maximum"""
     running_sum = 0
 
+    if not lst:
+        logger.warning("Empty message history passed to find_last_index")
+        return 0
+
     last_ind = 0
     for i in range(len(lst) - 1, -1, -1):
         running_sum += lst[i] + _PER_MESSAGE_TOKEN_BUFFER
         if running_sum > max_prompt_tokens:
             last_ind = i + 1
             break
+
     if last_ind >= len(lst):
+        logger.error(
+            f"Last message alone is too large! max_prompt_tokens: {max_prompt_tokens}, message_token_counts: {lst}"
+        )
         raise ValueError("Last message alone is too large!")
+
     return last_ind