diff --git a/docs/src/polynomial.md b/docs/src/polynomial.md
index 4c77a6a768..93efb3d789 100644
--- a/docs/src/polynomial.md
+++ b/docs/src/polynomial.md
@@ -95,8 +95,13 @@ the usual ways of constructing an element of a ring.
 (R::PolyRing)(c::elem_type(R))
 (R::PolyRing{T})(a::T) where T <: RingElement
 ```
+The third constructor above cannot be used to coerce a polynomial from one ring
+to another; instead use a call like `map_coefficients(identity, f; parent=dest_ring))`,
+or alternatively, for _small polynomials_ one can simply use evaluation:
+namely, `f(y)` where `y` is the generator of the destination polynomial ring.
+The fourth constructor creates a constant polynomial from an element of the coefficient ring.
 
-For polynommials there is also the following more general constructor accepting
+For polynomials there is also the following more general constructor accepting
 an array of coefficients.
 
 ```julia