diff --git a/vllm/v1/worker/gpu/sample/states.py b/vllm/v1/worker/gpu/sample/states.py
index bf2f1ce78f..fe4dee6a6b 100644
--- a/vllm/v1/worker/gpu/sample/states.py
+++ b/vllm/v1/worker/gpu/sample/states.py
@@ -56,6 +56,8 @@ class SamplingStates:
         num_logprobs = sampling_params.logprobs
         if num_logprobs is None:
             num_logprobs = NO_LOGPROBS
+        elif num_logprobs == -1:
+            num_logprobs = self.vocab_size
         self.num_logprobs[req_idx] = num_logprobs
 
     def apply_staged_writes(self) -> None: