diff --git a/gamutrf/grscan.py b/gamutrf/grscan.py
index 34c7b878..d426b0d2 100644
--- a/gamutrf/grscan.py
+++ b/gamutrf/grscan.py
@@ -349,8 +349,11 @@ def get_offload_fft_blocks(
                 * fft_batch_size
             ),
             fft_block,
-            blocks.vector_to_stream(gr.sizeof_gr_complex * nfft, fft_batch_size),
         ]
+        if fft_batch_size > 1:
+            fft_blocks.append(
+                blocks.vector_to_stream(gr.sizeof_gr_complex * nfft, fft_batch_size)
+            )
         if fft_roll:
             fft_blocks.append(self.iqtlabs.vector_roll(nfft))
         return fft_batch_size, fft_blocks
diff --git a/gamutrf/offline.py b/gamutrf/offline.py
index c6d4f332..d6e1bd78 100644
--- a/gamutrf/offline.py
+++ b/gamutrf/offline.py
@@ -41,7 +41,7 @@ def main():
                 "samp_rate": int(meta["sample_rate"]),
                 "sdr": "file:" + filename,
                 "pretune": True,
-                "inference_min_db": -1e9,
+                "fft_batch_size": 1,
             }
         )
         tb = grscan(**scan_args)