diff --git a/stdpopsim/catalog/MusMus/dfes.py b/stdpopsim/catalog/MusMus/dfes.py
index ad201badc..17277c518 100644
--- a/stdpopsim/catalog/MusMus/dfes.py
+++ b/stdpopsim/catalog/MusMus/dfes.py
@@ -43,7 +43,7 @@ def _BookerDFE():
         description=description,
         long_description=long_description,
         mutation_types=[neutral, negative],
-        proportions=[0.333, 0.664],
+        proportions=[0.334, 0.666],
         citations=citations,
     )