diff --git a/src/Mod/Sketcher/Gui/CommandConstraints.cpp b/src/Mod/Sketcher/Gui/CommandConstraints.cpp
index 289791edbd..778688c29d 100644
--- a/src/Mod/Sketcher/Gui/CommandConstraints.cpp
+++ b/src/Mod/Sketcher/Gui/CommandConstraints.cpp
@@ -6976,6 +6976,7 @@ void CmdSketcherConstrainSnellsLaw::activated(int iMsg)
         ui_Datum.labelEdit->setParamGrpPath(QByteArray("User parameter:BaseApp/History/SketcherRefrIndexRatio"));
         ui_Datum.labelEdit->setToLastUsedValue();
         ui_Datum.labelEdit->selectNumber();
+        ui_Datum.labelEdit->setSingleStep(0.05);
         // Unable to bind, because the constraint does not yet exist
 
         if (dlg.exec() != QDialog::Accepted) return;
diff --git a/src/Mod/Sketcher/Gui/EditDatumDialog.cpp b/src/Mod/Sketcher/Gui/EditDatumDialog.cpp
index 21ba1729bf..e85e0d8bbc 100644
--- a/src/Mod/Sketcher/Gui/EditDatumDialog.cpp
+++ b/src/Mod/Sketcher/Gui/EditDatumDialog.cpp
@@ -119,6 +119,7 @@ void EditDatumDialog::exec(bool atCursor)
             dlg.setWindowTitle(tr("Refractive index ratio", "Constraint_SnellsLaw"));
             ui_ins_datum->label->setText(tr("Ratio n2/n1:", "Constraint_SnellsLaw"));
             ui_ins_datum->labelEdit->setParamGrpPath(QByteArray("User parameter:BaseApp/History/SketcherRefrIndexRatio"));
+            ui_ins_datum->labelEdit->setSingleStep(0.05);
         }
         else {
             dlg.setWindowTitle(tr("Insert length"));
diff --git a/src/Mod/Sketcher/Gui/InsertDatum.ui b/src/Mod/Sketcher/Gui/InsertDatum.ui
index 52e6baae3a..fa0ee8964a 100644
--- a/src/Mod/Sketcher/Gui/InsertDatum.ui
+++ b/src/Mod/Sketcher/Gui/InsertDatum.ui
@@ -33,7 +33,7 @@
       </widget>
      </item>
      <item row="0" column="1">
-      <widget class="Gui::PrefQuantitySpinBox" name="labelEdit" native="true">
+      <widget class="Gui::PrefQuantitySpinBox" name="labelEdit">
        <property name="sizePolicy">
         <sizepolicy hsizetype="MinimumExpanding" vsizetype="Preferred">
          <horstretch>0</horstretch>
@@ -94,8 +94,13 @@
  </widget>
  <customwidgets>
   <customwidget>
-   <class>Gui::PrefQuantitySpinBox</class>
+   <class>Gui::QuantitySpinBox</class>
    <extends>QWidget</extends>
+   <header>Gui/QuantitySpinBox.h</header>
+  </customwidget>
+  <customwidget>
+   <class>Gui::PrefQuantitySpinBox</class>
+   <extends>Gui::QuantitySpinBox</extends>
    <header>Gui/PrefWidgets.h</header>
    <slots>
     <signal>showFormulaDialog(bool)</signal>