diff --git a/src/transformations/defmodel.hpp b/src/transformations/defmodel.hpp
index 1b0005b13e..6bf37d8be5 100644
--- a/src/transformations/defmodel.hpp
+++ b/src/transformations/defmodel.hpp
@@ -218,11 +218,11 @@ class Component {
     };
 
     struct PiecewiseTimeFunction : public TimeFunction {
-        /** One of "zero", "constant", and "linear", defines the behaviour of
+        /** One of "zero", "constant", and "linear", defines the behavior of
          * the function before the first defined epoch */
         std::string beforeFirst{};
 
-        /** One of "zero", "constant", and "linear", defines the behaviour of
+        /** One of "zero", "constant", and "linear", defines the behavior of
          * the function after the last defined epoch */
         std::string afterLast{};