diff --git a/binarycpython/utils/grid.py b/binarycpython/utils/grid.py
index 92332341c44f87e8d377d3e9842ffc92c3f19df1..4fb491b249d588badfbe996ed307952eef62c424 100644
--- a/binarycpython/utils/grid.py
+++ b/binarycpython/utils/grid.py
@@ -1943,7 +1943,7 @@ class Population:
             code_string += indent * (depth + 1) + "# Setting probabilities\n"
             code_string += (
                 indent * (depth + 1)
-                + "d{} = phasevol_{} * {}".format(
+                + "d{} = phasevol_{} * ({})".format(
                     grid_variable["name"],
                     grid_variable["name"],
                     grid_variable["probdist"],