diff --git a/typed-racket-lib/typed-racket/base-env/base-env-numeric.rkt b/typed-racket-lib/typed-racket/base-env/base-env-numeric.rkt
index 12b196935..ddc29b0a8 100644
--- a/typed-racket-lib/typed-racket/base-env/base-env-numeric.rkt
+++ b/typed-racket-lib/typed-racket/base-env/base-env-numeric.rkt
@@ -420,6 +420,13 @@
        (-> -NonPosInt -Int -NonPosFixnum)
        (binop -Int -Fixnum))))
 
+  (define fxpopcount-type
+    (lambda ()
+      (fx-from-cases
+       (-Nat . -> . -NonNegFixnum)
+       (-NonNegFixnum . -> . -NonNegFixnum)
+       (-Int . -> . -Fixnum))))
+
   ;; A bit of machinery to allow floating point operations to be abstracted over double/extended
   ;; floating point types without repetition. 
   (define-syntax (define-fl-type-lambda stx)
@@ -1946,6 +1953,10 @@
 [fxlshift (fxlshift-type)]
 [fxrshift (fxrshift-type)]
 
+[fxpopcount (fxpopcount-type)]
+[fxpopcount16 (fxpopcount-type)]
+[fxpopcount32 (fxpopcount-type)]
+
 [fx= (fx=-type)]
 [fx< (fx<-type)]
 [fx> (fx>-type)]
diff --git a/typed-racket-test/succeed/fixnum.rkt b/typed-racket-test/succeed/fixnum.rkt
index e679832ee..fe3c836ce 100644
--- a/typed-racket-test/succeed/fixnum.rkt
+++ b/typed-racket-test/succeed/fixnum.rkt
@@ -38,3 +38,6 @@
 (check equal? (fxmin 3 2) 2)
 (check equal? (fxmax 3 4) 4)
 
+(check equal? (fxpopcount #x0fffffffffffffff) 60)
+(check equal? (fxpopcount32 #xffffffff) 32)
+(check equal? (fxpopcount16 #xffff) 16)