diff --git a/src/libslic3r/Config.cpp b/src/libslic3r/Config.cpp
index e3f24d2292..88e0c76646 100644
--- a/src/libslic3r/Config.cpp
+++ b/src/libslic3r/Config.cpp
@@ -336,7 +336,7 @@ double ConfigBase::get_abs_value(const t_config_option_key &opt_key, double rati
     return static_cast<const ConfigOptionFloatOrPercent*>(raw_opt)->get_abs_value(ratio_over);
 }
 
-void ConfigBase::setenv_()
+void ConfigBase::setenv_() const
 {
     t_config_option_keys opt_keys = this->keys();
     for (t_config_option_keys::const_iterator it = opt_keys.begin(); it != opt_keys.end(); ++it) {
diff --git a/src/libslic3r/Config.hpp b/src/libslic3r/Config.hpp
index b5a44e1768..7f826109a4 100644
--- a/src/libslic3r/Config.hpp
+++ b/src/libslic3r/Config.hpp
@@ -1113,7 +1113,7 @@ public:
 
     double get_abs_value(const t_config_option_key &opt_key) const;
     double get_abs_value(const t_config_option_key &opt_key, double ratio_over) const;
-    void setenv_();
+    void setenv_() const;
     void load(const std::string &file);
     void load_from_ini(const std::string &file);
     void load_from_gcode_file(const std::string &file);