diff --git a/environment.yml b/environment.yml
index d34d498..a78fab3 100644
--- a/environment.yml
+++ b/environment.yml
@@ -11,7 +11,7 @@ dependencies:
 - psutil
 - birdy
 #- tigramite
-#- tefs
+#- tefs==0.3.1
 - pandas
 - scikit-learn
 - numpy
diff --git a/requirements.txt b/requirements.txt
index f89c934..2bcfac0 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,7 +4,7 @@ psutil
 pywps>=4.5.1,<4.6
 birdhouse-birdy
 tigramite>=5.2.5.1
-tefs
+tefs==0.3.1
 pandas
 scikit-learn
 numpy
\ No newline at end of file