diff --git a/ortools/math_opt/cpp/variable_and_expressions.h b/ortools/math_opt/cpp/variable_and_expressions.h
index bfebd53bfed..02a0f2c5e87 100644
--- a/ortools/math_opt/cpp/variable_and_expressions.h
+++ b/ortools/math_opt/cpp/variable_and_expressions.h
@@ -3157,8 +3157,8 @@ namespace std {
            const ::operations_research::math_opt::Variable& rhs ) const {
          return lhs == rhs;
        }
-  }
-}
+  };
+}  // namespace std
 #endif
 
 #endif  // OR_TOOLS_MATH_OPT_CPP_VARIABLE_AND_EXPRESSIONS_H_