diff --git a/CGAL_Core/include/CGAL/CORE/Expr.h b/CGAL_Core/include/CGAL/CORE/Expr.h
index c10fb5fc560..e6efa1feb7c 100644
--- a/CGAL_Core/include/CGAL/CORE/Expr.h
+++ b/CGAL_Core/include/CGAL/CORE/Expr.h
@@ -91,9 +91,14 @@ public:
   Expr(const BigInt& I) : RCExpr(new ConstRealRep(Real(I))) {}
   /// constructor for <tt>BigRat</tt>
   Expr(const BigRat& R) : RCExpr(new ConstRealRep(Real(R))) {}
-  /// constructor for <tt>BigRat expression</tt>
-  template <class BigRatExpr, class = std::enable_if_t< boost::multiprecision::is_number_expression<BigRatExpr>::value> >
-  Expr(const BigRatExpr& R) : RCExpr(new ConstRealRep(Real(BigRat(R)))) {}
+  /// constructor from expression template
+  template <class TmplExpr,
+            class = std::enable_if_t<
+              boost::multiprecision::is_number_expression<TmplExpr>::value> >
+  Expr(const TmplExpr& R)
+    : RCExpr(new ConstRealRep(Real(
+        std::conditional_t<boost::multiprecision::number_category<TmplExpr>::value == boost::multiprecision::number_kind_integer,
+        BigInt, BigRat>(R)))) {}
 
   /// constructor for <tt>BigFloat</tt>
   Expr(const BigFloat& F) : RCExpr(new ConstRealRep(Real(F))) {}