diff --git a/collects/typed-racket/base-env/prims.rkt b/collects/typed-racket/base-env/prims.rkt
index dd4b29ff..6f42fbba 100644
--- a/collects/typed-racket/base-env/prims.rkt
+++ b/collects/typed-racket/base-env/prims.rkt
@@ -642,7 +642,6 @@ This file defines two sorts of primitives. All of them are provided into any mod
   (for/last: for/last)
   (for/vector: for/vector)
   (for/flvector: for/flvector)
-  (for/sum: for/sum)
   (for/product: for/product))
 
 ;; Unlike with the above, the inferencer can handle any number of #:when
@@ -694,6 +693,7 @@ This file defines two sorts of primitives. All of them are provided into any mod
       'type-ascription
       #'(values var.ty ...))]))
 
+
 (define-syntax (for*: stx)
   (syntax-parse stx #:literals (:)
     [(_ (~seq : Void) ...
@@ -733,7 +733,6 @@ This file defines two sorts of primitives. All of them are provided into any mod
   (for*/last: for*/last)
   (for*/vector: for*/vector)
   (for*/flvector: for*/flvector)
-  (for*/sum: for*/sum)
   (for*/product: for*/product))
 
 ;; Like for/lists: and for/fold:, the inferencer can handle these correctly.
@@ -784,6 +783,32 @@ This file defines two sorts of primitives. All of them are provided into any mod
       'type-ascription
       #'(values var.ty ...))]))
 
+
+(define-for-syntax (define-for/sum:-variant for/folder)
+  (lambda (stx)
+    (syntax-parse stx #:literals (:)
+      [(_ : ty
+          (clause:for-clause ...)
+          c:expr ...)
+       ;; ty has to include exact 0, the initial value of the accumulator
+       ;; (to be consistent with Racket semantics).
+       ;; We can't just change the initial value to be 0.0 if we expect a
+       ;; Float result. This is problematic in some cases e.g:
+       ;; (for/sum: : Float ([i : Float '(1.1)] #:when (zero? (random 1))) i)
+       (quasisyntax/loc stx
+         (#,for/folder : ty ([acc : ty 0])
+                       (clause.expand ... ...)
+                       (let ([new (let () c ...)])
+                         (+ acc new))))])))
+(define-syntax (define-for/sum:-variants stx)
+  (syntax-parse stx
+    [(_ (name for/folder) ...)
+     (quasisyntax/loc stx
+       (begin (define-syntax name (define-for/sum:-variant #'for/folder))
+              ...))]))
+(define-for/sum:-variants (for/sum: for/fold:) (for*/sum: for*/fold:))
+
+
 (define-syntax (provide: stx)
   (syntax-parse stx
     [(_ [i:id t] ...)