diff --git a/vllm/v1/attention/backends/rocm_aiter_fa.py b/vllm/v1/attention/backends/rocm_aiter_fa.py
index 7e850af3e7..0f289649b1 100644
--- a/vllm/v1/attention/backends/rocm_aiter_fa.py
+++ b/vllm/v1/attention/backends/rocm_aiter_fa.py
@@ -602,7 +602,11 @@ class AiterFlashAttentionMetadataBuilder(
             torch.cumsum(
                 chunk_seq_lens, dim=1, out=cu_seq_lens_cpu[:, 1:], dtype=torch.int32
             )
-            max_cum_tokens = cu_seq_lens_cpu[:, -1].max().item()
+            # Avoid .max() on an empty tensor when there is no context
+            # (num_chunks == 0, e.g. Whisper encoder's first pass).
+            max_cum_tokens = (
+                cu_seq_lens_cpu[:, -1].max().item() if num_chunks > 0 else 0
+            )
 
             range_idx = torch.arange(max_cum_tokens, dtype=torch.int32)[None, None, :]
             idx_to_batch_tensor = range_idx == cu_seq_lens_cpu[:, 1:][:, :, None]