diff --git a/bend2/base.bend b/bend2/base.bend
index 21979b7487..aa6714de26 100644
--- a/bend2/base.bend
+++ b/bend2/base.bend
@@ -1863,11 +1863,20 @@ def F32.hypot(a: F32, b: F32) -> F32:
   +q = F32.mul(y, s)
   F32.mul(F32.sqrt(F32.add(F32.mul(p, p), F32.mul(q, q))), u)
 
+# A rounded zero keeps the input sign, including at the negative half.
+def F32.round.zero(a: F32, r: F32, zero: Bool) -> F32:
+  match zero:
+    case True{}:
+      F32.mul(a, 0.0)
+    case False{}:
+      r
+
 def F32.round(a: F32) -> F32:
   match a:
     case F32{+x}:
       +f = F32.floor(F32{x})
-      F32.add(f, Bool.pick(F32, F32.is_ge(F32.sub(F32{x}, f), 0.5), 1.0, 0.0))
+      +r = F32.add(f, Bool.pick(F32, F32.is_ge(F32.sub(F32{x}, f), 0.5), 1.0, 0.0))
+      F32.round.zero(F32{x}, r, F32.is_eq(r, 0.0))
 
 def F32.pi() -> F32:
   3.14159265
diff --git a/tests/base/f32_round_zero.bend b/tests/base/f32_round_zero.bend
new file mode 100644
index 0000000000..21a4c4e01e
--- /dev/null
+++ b/tests/base/f32_round_zero.bend
@@ -0,0 +1,13 @@
+import Base
+
+def main() -> IO(Unit):
+  do IO<Unit>:
+    IO.print(U32.show(F32.bits(F32.round(F32.neg(0.0)))))
+    IO.print(Bool.show(F32.is_eq(F32.div(1.0, F32.round(F32.neg(0.1))), F32.div(F32.neg(1.0), 0.0))))
+    IO.print(U32.show(F32.bits(F32.round(F32.neg(0.5)))))
+    IO.print(Bool.show(F32.is_eq(F32.round(F32.neg(0.5000000596046448)), F32.neg(1.0))))
+
+#|2147483648
+#|True
+#|2147483648
+#|True