diff --git a/collects/racket/contract/private/helpers.rkt b/collects/racket/contract/private/helpers.rkt
index 84ad6340a0..dfdcd5ee6f 100644
--- a/collects/racket/contract/private/helpers.rkt
+++ b/collects/racket/contract/private/helpers.rkt
@@ -161,137 +161,210 @@
       [(= i n) '()]
       [else (cons i (loop (+ i 1)))])))
 
-(define known-good-ids
-  (list #'absolute-path?
-        #'bound-identifier=?
-        #'box?
-        #'byte-pregexp?
-        #'byte-regexp?
-        #'byte?
-        #'bytes-converter?
-        #'bytes=?
-        #'bytes?
-        #'channel?
-        #'char-alphabetic?
-        #'char-blank?
-        #'char-graphic?
-        #'char-iso-control?
-        #'char-lower-case?
-        #'char-numeric?
-        #'char-punctuation?
-        #'char-symbolic?
-        #'char-title-case?
-        #'char-upper-case?
-        #'char-whitespace?
-        #'compiled-expression?
-        #'compiled-module-expression?
-        #'complete-path?
-        #'continuation-mark-set?
-        #'continuation-prompt-available?
-        #'custodian-box?
-        #'custodian-memory-accounting-available?
-        #'custodian?
-        #'directory-exists?
-        #'ephemeron?
-        #'evt?
-        #'exn:break?
-        #'exn:fail:contract:arity?
-        #'exn:fail:contract:continuation?
-        #'exn:fail:contract:divide-by-zero?
-        #'exn:fail:contract:variable?
-        #'exn:fail:contract?
-        #'exn:fail:filesystem:exists?
-        #'exn:fail:filesystem:version?
-        #'exn:fail:filesystem?
-        #'exn:fail:network?
-        #'exn:fail:out-of-memory?
-        #'exn:fail:read:eof?
-        #'exn:fail:read:non-char?
-        #'exn:fail:read?
-        #'exn:fail:syntax?
-        #'exn:fail:unsupported?
-        #'exn:fail:user?
-        #'exn:fail?
-        #'exn?
-        #'file-exists?
-        #'file-stream-port?
-        #'free-identifier=?
-        #'handle-evt?
-        #'hash-table?
-        #'identifier?
-        #'immutable?
-        #'inspector?
-        #'keyword?
-        #'link-exists?
-        #'module-identifier=?
-        #'module-path-index?
-        #'module-provide-protected?
-        #'module-template-identifier=?
-        #'module-transformer-identifier=?
-        #'namespace?
-        #'parameter-procedure=?
-        #'parameter?
-        #'parameterization?
-        #'path-for-some-system?
-        #'path-string?
-        #'path?
-        #'port-closed?
-        #'port-provides-progress-evts?
-        #'port-writes-atomic?
-        #'port-writes-special?
-        #'port?
-        #'pregexp?
-        #'primitive-closure?
-        #'primitive?
-        #'procedure-arity-includes?
-        #'procedure-closure-contents-eq?
-        #'procedure-struct-type?
-        #'promise?
-        #'pseudo-random-generator?
-        #'regexp-match?
-        #'regexp?
-        #'relative-path?
-        #'rename-transformer?
-        #'security-guard?
-        #'semaphore-try-wait?
-        #'semaphore?
-        #'set!-transformer?
-        #'special-comment?
-        #'string-locale-ci=?
-        #'string-locale=?
-        #'struct-accessor-procedure?
-        #'struct-constructor-procedure?
-        #'struct-mutator-procedure?
-        #'struct-predicate-procedure?
-        #'struct-type-property?
-        #'struct-type?
-        #'struct?
-        #'subprocess?
-        #'syntax-graph?
-        #'syntax-original?
-        #'syntax-transforming?
-        #'syntax?
-        #'system-big-endian?
-        #'tcp-accept-ready?
-        #'tcp-listener?
-        #'tcp-port?
-        #'terminal-port?
-        #'thread-cell?
-        #'thread-dead?
-        #'thread-group?
-        #'thread-running?
-        #'thread?
-        #'udp-bound?
-        #'udp-connected?
-        #'udp?
-        #'void?
-        #'weak-box?
-        #'will-executor?
-        #'arity-at-least?
-        #'exn:srclocs?
-        #'srcloc?))
+#|
+
+;; the code below builds the known-good-syms-ht
+
+(define cm
+  (parameterize ([read-accept-compiled #t])
+    (call-with-input-file
+        "C:\\Users\\robby\\git\\plt\\collects\\racket\\compiled\\base_rkt.zo" read)))
+
+(define ns (make-base-namespace))
+(parameterize ([current-namespace ns])
+  (namespace-require 'racket/base))
+
+(define-values (vars stx) (module-compiled-exports cm))
+(define known-good-syms 
+  (filter (λ (x) (and (regexp-match #rx"[?]$" (symbol->string x))
+                      (procedure-arity-includes? (eval x ns) 1)))
+          (map car (cdr (assoc 0 vars)))))
+(define table-to-be-turned-into-a-literal-hash
+  (map (λ (x) (cons x #t))
+       (sort known-good-syms
+             string<=?
+             #:key symbol->string)))
+
+|#
+
+(define known-good-syms-ht 
+  '#hash((absolute-path? . #t)
+         (arity-at-least? . #t)
+         (boolean? . #t)
+         (box? . #t)
+         (byte-pregexp? . #t)
+         (byte-ready? . #t)
+         (byte-regexp? . #t)
+         (byte? . #t)
+         (bytes-converter? . #t)
+         (bytes? . #t)
+         (channel? . #t)
+         (chaperone? . #t)
+         (char-alphabetic? . #t)
+         (char-blank? . #t)
+         (char-graphic? . #t)
+         (char-iso-control? . #t)
+         (char-lower-case? . #t)
+         (char-numeric? . #t)
+         (char-punctuation? . #t)
+         (char-ready? . #t)
+         (char-symbolic? . #t)
+         (char-title-case? . #t)
+         (char-upper-case? . #t)
+         (char-whitespace? . #t)
+         (char? . #t)
+         (compiled-expression? . #t)
+         (compiled-module-expression? . #t)
+         (complete-path? . #t)
+         (complex? . #t)
+         (continuation-mark-set? . #t)
+         (continuation-prompt-available? . #t)
+         (continuation-prompt-tag? . #t)
+         (continuation? . #t)
+         (custodian-box? . #t)
+         (custodian? . #t)
+         (custom-print-quotable? . #t)
+         (custom-write? . #t)
+         (date*? . #t)
+         (date-dst? . #t)
+         (date? . #t)
+         (directory-exists? . #t)
+         (double-flonum? . #t)
+         (eof-object? . #t)
+         (ephemeron? . #t)
+         (even? . #t)
+         (evt? . #t)
+         (exact-integer? . #t)
+         (exact-nonnegative-integer? . #t)
+         (exact-positive-integer? . #t)
+         (exact? . #t)
+         (exn:break? . #t)
+         (exn:fail:contract:arity? . #t)
+         (exn:fail:contract:continuation? . #t)
+         (exn:fail:contract:divide-by-zero? . #t)
+         (exn:fail:contract:non-fixnum-result? . #t)
+         (exn:fail:contract:variable? . #t)
+         (exn:fail:contract? . #t)
+         (exn:fail:filesystem:exists? . #t)
+         (exn:fail:filesystem:version? . #t)
+         (exn:fail:filesystem? . #t)
+         (exn:fail:network? . #t)
+         (exn:fail:out-of-memory? . #t)
+         (exn:fail:read:eof? . #t)
+         (exn:fail:read:non-char? . #t)
+         (exn:fail:read? . #t)
+         (exn:fail:syntax:unbound? . #t)
+         (exn:fail:syntax? . #t)
+         (exn:fail:unsupported? . #t)
+         (exn:fail:user? . #t)
+         (exn:fail? . #t)
+         (exn:srclocs? . #t)
+         (exn? . #t)
+         (file-exists? . #t)
+         (file-stream-port? . #t)
+         (fixnum? . #t)
+         (flonum? . #t)
+         (handle-evt? . #t)
+         (hash-eq? . #t)
+         (hash-equal? . #t)
+         (hash-eqv? . #t)
+         (hash-placeholder? . #t)
+         (hash-weak? . #t)
+         (hash? . #t)
+         (identifier? . #t)
+         (immutable? . #t)
+         (impersonator-property-accessor-procedure? . #t)
+         (impersonator-property? . #t)
+         (impersonator? . #t)
+         (inexact-real? . #t)
+         (inexact? . #t)
+         (input-port? . #t)
+         (inspector? . #t)
+         (integer? . #t)
+         (internal-definition-context? . #t)
+         (keyword? . #t)
+         (liberal-define-context? . #t)
+         (link-exists? . #t)
+         (list? . #t)
+         (log-receiver? . #t)
+         (logger? . #t)
+         (module-path-index? . #t)
+         (module-path? . #t)
+         (mpair? . #t)
+         (namespace-anchor? . #t)
+         (namespace? . #t)
+         (negative? . #t)
+         (null? . #t)
+         (number? . #t)
+         (odd? . #t)
+         (output-port? . #t)
+         (pair? . #t)
+         (parameter? . #t)
+         (parameterization? . #t)
+         (path-for-some-system? . #t)
+         (path-string? . #t)
+         (path? . #t)
+         (placeholder? . #t)
+         (port-closed? . #t)
+         (port-provides-progress-evts? . #t)
+         (port-writes-atomic? . #t)
+         (port-writes-special? . #t)
+         (port? . #t)
+         (positive? . #t)
+         (pregexp? . #t)
+         (primitive-closure? . #t)
+         (primitive? . #t)
+         (procedure-arity? . #t)
+         (procedure-struct-type? . #t)
+         (procedure? . #t)
+         (pseudo-random-generator? . #t)
+         (rational? . #t)
+         (readtable? . #t)
+         (real? . #t)
+         (regexp? . #t)
+         (relative-path? . #t)
+         (rename-transformer? . #t)
+         (resolved-module-path? . #t)
+         (security-guard? . #t)
+         (semaphore-try-wait? . #t)
+         (semaphore? . #t)
+         (sequence? . #t)
+         (set!-transformer? . #t)
+         (single-flonum? . #t)
+         (special-comment? . #t)
+         (srcloc? . #t)
+         (string? . #t)
+         (struct-accessor-procedure? . #t)
+         (struct-constructor-procedure? . #t)
+         (struct-mutator-procedure? . #t)
+         (struct-predicate-procedure? . #t)
+         (struct-type-property-accessor-procedure? . #t)
+         (struct-type-property? . #t)
+         (struct-type? . #t)
+         (struct? . #t)
+         (subprocess? . #t)
+         (symbol-interned? . #t)
+         (symbol-unreadable? . #t)
+         (symbol? . #t)
+         (syntax-original? . #t)
+         (syntax-tainted? . #t)
+         (syntax? . #t)
+         (terminal-port? . #t)
+         (thread-cell? . #t)
+         (thread-dead? . #t)
+         (thread-group? . #t)
+         (thread-running? . #t)
+         (thread? . #t)
+         (variable-reference-constant? . #t)
+         (variable-reference? . #t)
+         (vector? . #t)
+         (void? . #t)
+         (weak-box? . #t)
+         (will-executor? . #t)
+         (zero? . #t)))
 
 (define (known-good-contract? id)
-  (and (identifier? id)
-       (ormap (λ (x) (free-identifier=? x id))
-              known-good-ids)))
+  (define r-id (syntax-e id))
+  (and (symbol? r-id)
+       (hash-ref known-good-syms-ht (syntax-e id) #t)
+       (free-identifier=? id (datum->syntax #'here r-id))))