diff --git a/doc/src/manual/types.md b/doc/src/manual/types.md
index 17314f8d1d288..7179ce78969a1 100644
--- a/doc/src/manual/types.md
+++ b/doc/src/manual/types.md
@@ -301,7 +301,7 @@ a name. A primitive type can optionally be declared to be a subtype of some supe
 is omitted, then the type defaults to having `Any` as its immediate supertype. The declaration
 of [`Bool`](@ref) above therefore means that a boolean value takes eight bits to store, and has
 [`Integer`](@ref) as its immediate supertype. Currently, only sizes that are multiples of
-8 bits are supported.
+8 bits are supported and you are likely to experience Julia or LLVM bugs with sizes other than those used above.
 Therefore, boolean values, although they really need just a single bit, cannot be declared to be any
 smaller than eight bits.