diff --git a/k2/csrc/rnnt_decode.h b/k2/csrc/rnnt_decode.h
index aa227970f..6ef168e05 100644
--- a/k2/csrc/rnnt_decode.h
+++ b/k2/csrc/rnnt_decode.h
@@ -182,8 +182,9 @@ class RnntDecodingStreams {
                     ever received).
                     It MUST satisfy `num_frames.size() == num_streams_`, and
                     `num_frames[i] <= srcs_[i].prev_frames.size()`.
-      @param [in] allow_partial If true, we will treat all the states on the
-                                last frame to be final state. If false, we only
+      @param [in] allow_partial If true and there is no final state active,
+                                we will treat all the states on the last frame
+                                to be final state. If false, we only
                                 care about the real final state in the decoding
                                 graph on the last frame when generating lattice.
       @param [out] ofsa  The output lattice will write to here, its num_axes
diff --git a/k2/python/k2/rnnt_decode.py b/k2/python/k2/rnnt_decode.py
index 76ff614d9..95f6aa8ab 100644
--- a/k2/python/k2/rnnt_decode.py
+++ b/k2/python/k2/rnnt_decode.py
@@ -168,8 +168,9 @@ def format_output(
             stream (note: the frames we have ever received for the corresponding
             stream). It MUST satisfy `len(num_frames) == self.num_streams`.
           allow_partial:
-            If true, we will treat all the states on the last frame to be final
-            state. If false, we only care about the real final state in the
+            If true and there is no final state active, we will treat all the
+            states on the last frame to be final state.
+            If false, we only care about the real final state in the
             decoding graph on the last frame when generating lattice.
             Default False.