diff --git a/collects/scribblings/foreign/types.scrbl b/collects/scribblings/foreign/types.scrbl
index 595968b27e..44975a2e96 100644
--- a/collects/scribblings/foreign/types.scrbl
+++ b/collects/scribblings/foreign/types.scrbl
@@ -282,7 +282,9 @@ PLT Scheme's C API.}
 Similar to @scheme[_pointer], except that when an @scheme[_fpointer]
 is extracted from a pointer produced by @scheme[ffi-obj-ref], then a
 level of indirection is skipped. A level of indirection is similarly
-skipped when extracting a pointer via @scheme[get-ffi-obj].
+skipped when extracting a pointer via @scheme[get-ffi-obj]. Also
+unlike @scheme[_pointer], @scheme[_fpointer] does not convert
+@scheme[#f] to @cpp{NULL}.
 
 A type generated by @scheme[_cprocedure] builds on @scheme[_fpointer],
 and normally @scheme[_cprocedure] should be used instead of
@@ -439,9 +441,11 @@ For example,
 specifies a function that receives an integer and a string, but the
 foreign function receives the string first.}
 
-@defproc[(function-ptr [ptr cpointer?] [fun-type ctype?]) cpointer?]{
+@defproc[(function-ptr [ptr-or-proc (or cpointer? procedure?)]
+                       [fun-type ctype?])
+         cpointer?]{
 
-Casts @scheme[ptr] to a function pointer of type @scheme[fun-type].}
+Casts @scheme[ptr-or-proc] to a function pointer of type @scheme[fun-type].}
 
 @; ----------------------------------------------------------------------