diff --git a/server/text_generation_server/models/flash_causal_lm.py b/server/text_generation_server/models/flash_causal_lm.py
index 7e048b7..c44dd57 100644
--- a/server/text_generation_server/models/flash_causal_lm.py
+++ b/server/text_generation_server/models/flash_causal_lm.py
@@ -453,7 +453,10 @@ class FlashCausalLM(Model):
                 )
             # Set in batch in case it needs to be used later in concatenate()
             batch.past_pad = self.past_pad
-            if len(batch) != 1:
+            if len(batch) == 1:
+                # present is already pre-padded
+                batch.past_key_values = present
+            else:
                 # Add padding after each sequence
                 # This will have the correct shape after the final past_key_values concatenation before the model
                 # forward