diff --git a/ivas_processing_scripts/processing/evs.py b/ivas_processing_scripts/processing/evs.py
index 6697a71ac1be1f1ea74a11a5f6ed1f391c55a086..80b9fe14a2df608e1ad23e43008555492fbadb2f 100755
--- a/ivas_processing_scripts/processing/evs.py
+++ b/ivas_processing_scripts/processing/evs.py
@@ -216,12 +216,15 @@ class EVS(Processing):
         )
 
         # apply bitstream processing and save unprocessed bitstream
+        # Important: don't apply parallel processing - simulate_tx() generates error patterns and applies them;
+        # however, the error patterns have the same name, i.e. running these tasks in parallel might lead
+        # to collisions and eventually cause issues with being deterministic across multiple runs
         split_chan_bs_unprocessed = split_chan_bs
         split_chan_bs = apply_func_parallel(
             self.simulate_tx,
             zip(split_chan_files, split_chan_bs, repeat(logger)),
             None,
-            "mt" if self.multiprocessing else None,
+            None,
             show_progress=False,
         )
         voip = [scb[1] for scb in split_chan_bs]