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 fac22f1e..7da48d8e 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
@@ -889,12 +889,14 @@
 
 ;; numeric predicates
 ;; There are 25 values that answer true to zero?. They are either reals, or inexact complexes.
+;; Note -RealZero contains NaN and zero? returns #f on it
 [zero?
   (cl->*
     (-> -ExactNumber B : (-FS (-filter (-val 0) 0) (-not-filter (-val 0) 0)))
-    (-> -Real B : (-FS (-filter -RealZero 0) (-not-filter -RealZero 0)))
+    (-> -Real B : (-FS (-filter -RealZero 0)
+                       (-not-filter (Un -Zero -InexactRealPosZero -InexactRealNegZero) 0)))
     (-> N B : (-FS (-filter (Un -RealZero -InexactComplex -InexactImaginary) 0)
-                   (-not-filter -RealZero 0))))]
+                   (-not-filter (Un -Zero -InexactRealPosZero -InexactRealNegZero) 0))))]
 
 [number? (make-pred-ty N)]
 [integer? (asym-pred Univ B (-FS (-filter (Un -Int -Flonum -SingleFlonum) 0) ; inexact-integers exist...
diff --git a/typed-racket-test/unit-tests/typecheck-tests.rkt b/typed-racket-test/unit-tests/typecheck-tests.rkt
index 9d8d0123..e42019ef 100644
--- a/typed-racket-test/unit-tests/typecheck-tests.rkt
+++ b/typed-racket-test/unit-tests/typecheck-tests.rkt
@@ -3562,6 +3562,9 @@
                       (error "foo"))
                #:extend-env ([foo-x (t:-> (-prefab 'foo -String) -String)])
                #:msg #rx"expected: \\(Prefab foo.*given: \\(Prefab bar"]
+       [tc-e/t
+         (lambda: ([x : Real-Zero]) (or (zero? x) x))
+         (t:-> -RealZero (t:Un (-val #t) -InexactRealNan) : -true-filter)]
        )
 
   (test-suite