diff --git a/src/ui/qgsexpressionselectiondialogbase.ui b/src/ui/qgsexpressionselectiondialogbase.ui
index 18a27c1f4e8..3aad09956a2 100644
--- a/src/ui/qgsexpressionselectiondialogbase.ui
+++ b/src/ui/qgsexpressionselectiondialogbase.ui
@@ -68,6 +68,12 @@
    </item>
    <item row="1" column="0">
     <widget class="QDialogButtonBox" name="buttonBox">
+     <property name="sizePolicy">
+      <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
+       <horstretch>0</horstretch>
+       <verstretch>0</verstretch>
+      </sizepolicy>
+     </property>
      <property name="standardButtons">
       <set>QDialogButtonBox::Help</set>
      </property>