diff --git a/bpc-requirements.txt b/bpc-requirements.txt
index 99d91eb..8979cef 100644
--- a/bpc-requirements.txt
+++ b/bpc-requirements.txt
@@ -10,7 +10,7 @@ pybids
 nibabel
 nilearn
 
-pymef >= 1.3.6
+pymef == 1.3.4
 
 tqdm
 ipykernel
\ No newline at end of file