diff --git a/src/slic3r/GUI/CalibrationWizard.cpp b/src/slic3r/GUI/CalibrationWizard.cpp
index 736143ccef..b0a2007ba5 100644
--- a/src/slic3r/GUI/CalibrationWizard.cpp
+++ b/src/slic3r/GUI/CalibrationWizard.cpp
@@ -16,7 +16,7 @@ wxDEFINE_EVENT(EVT_CALIBRATION_JOB_FINISHED, wxCommandEvent);
 
 static const wxString NA_STR = _L("N/A");
 static const float MIN_PA_K_VALUE = 0.0;
-static const float MAX_PA_K_VALUE = 0.5;
+static const float MAX_PA_K_VALUE = 0.3;
 static const float MIN_PA_K_VALUE_STEP = 0.001;
 
 bool check_preset_name_valid(const wxString& name) {
diff --git a/src/slic3r/Utils/CalibUtils.cpp b/src/slic3r/Utils/CalibUtils.cpp
index 0fdf061409..fa34b1a6e0 100644
--- a/src/slic3r/Utils/CalibUtils.cpp
+++ b/src/slic3r/Utils/CalibUtils.cpp
@@ -100,7 +100,7 @@ bool CalibUtils::validate_input_k_value(wxString k_text, float* output_value)
         ;
     }
 
-    if (k_value < 0 || k_value > 0.5) {
+    if (k_value < 0 || k_value > 0.3) {
         *output_value = default_k;
         return false;
     }