diff --git a/src/libslic3r/calib.cpp b/src/libslic3r/calib.cpp
index f97db88211..508e7a4fd4 100644
--- a/src/libslic3r/calib.cpp
+++ b/src/libslic3r/calib.cpp
@@ -159,7 +159,6 @@ namespace Slic3r {
     }
 
     std::string calib_pressure_advance::draw_number(double startx, double starty, double value, calib_pressure_advance::DrawDigitMode mode) {
-        double spacing = 3.0;
         auto sNumber = std::to_string(value);
         sNumber.erase(sNumber.find_last_not_of('0') + 1, std::string::npos);
         sNumber.erase(sNumber.find_last_not_of('.') + 1, std::string::npos);
@@ -167,10 +166,9 @@ namespace Slic3r {
         gcode << mp_gcodegen->writer().set_speed(3600);
 
         for (int i = 0; i < sNumber.length(); ++i) {
-            if (i > 5)
+            if (i > m_max_number_length)
                 break;
-            gcode << draw_digit(startx + i * spacing, starty, sNumber[i], mode);
-
+            gcode << draw_digit(startx + i * m_number_spacing, starty, sNumber[i], mode);
         }
 
         return gcode.str();
diff --git a/src/libslic3r/calib.hpp b/src/libslic3r/calib.hpp
index b87c775129..f8cfb099ee 100644
--- a/src/libslic3r/calib.hpp
+++ b/src/libslic3r/calib.hpp
@@ -39,6 +39,9 @@ private:
     std::string move_to(Vec2d pt);
     std::string draw_digit(double startx, double starty, char c, calib_pressure_advance::DrawDigitMode mode);
     std::string draw_number(double startx, double starty, double value, calib_pressure_advance::DrawDigitMode mode);
+private:
+    int m_max_number_length {5};
+    double m_number_spacing {3.0};
 }
 
 class calib_pressure_advance_line: public calib_pressure_advance