diff --git a/base/docs/basedocs.jl b/base/docs/basedocs.jl
index c102a3b2ce426..8cb5c021fabc9 100644
--- a/base/docs/basedocs.jl
+++ b/base/docs/basedocs.jl
@@ -2523,14 +2523,14 @@ union [`Union{}`](@ref) is the bottom type of Julia.
 julia> IntOrString = Union{Int,AbstractString}
 Union{Int64, AbstractString}
 
-julia> 1 :: IntOrString
-1
+julia> 1 isa IntOrString
+true
 
-julia> "Hello!" :: IntOrString
-"Hello!"
+julia> "Hello!" isa IntOrString
+true
 
-julia> 1.0 :: IntOrString
-ERROR: TypeError: in typeassert, expected Union{Int64, AbstractString}, got a value of type Float64
+julia> 1.0 isa IntOrString
+false
 ```
 """
 Union