diff --git a/src/smriprep/interfaces/freesurfer.py b/src/smriprep/interfaces/freesurfer.py
index 94cd2960fa..989676ae69 100644
--- a/src/smriprep/interfaces/freesurfer.py
+++ b/src/smriprep/interfaces/freesurfer.py
@@ -337,4 +337,4 @@ def _format_arg(self, name, trait_spec, value):
 
     def _num_threads_update(self):
         if self.inputs.num_threads:
-            self.inputs.environ.update({'OMP_NUM_THREADS': str(self.inputs.num_threads * 3 // 2)})
+            self.inputs.environ.update({'OMP_SCHEDULE': 'dynamic', 'OMP_NUM_THREADS': str(max(1, min(8, self.inputs.num_threads - 1)))})