diff --git a/src/slic3r/GUI/calib_dlg.cpp b/src/slic3r/GUI/calib_dlg.cpp
index e053e601bd..2d0b9c1bec 100644
--- a/src/slic3r/GUI/calib_dlg.cpp
+++ b/src/slic3r/GUI/calib_dlg.cpp
@@ -166,7 +166,7 @@ void PA_Calibration_Dlg::reset_params() {
     if (!isDDE) {
         m_tiEndPA->GetTextCtrl()->SetValue(wxString::FromDouble(1.0));
         
-        if (m_params.mode = CalibMode::Calib_PA_Pattern) {
+        if (m_params.mode == CalibMode::Calib_PA_Pattern) {
             m_tiPAStep->GetTextCtrl()->SetValue(wxString::FromDouble(0.05));
         } else {
             m_tiPAStep->GetTextCtrl()->SetValue(wxString::FromDouble(0.02));