diff --git a/src/runtime/runtime1.go b/src/runtime/runtime1.go
index d5f78ba..85a9ba2 100644
--- a/src/runtime/runtime1.go
+++ b/src/runtime/runtime1.go
@@ -416,7 +416,9 @@
 	for bit := 30; bit >= 0; bit-- {
 		if v >= int64(div)<<uint(bit) {
 			v = v - (int64(div) << uint(bit))
-			res += 1 << uint(bit)
+			// Before this for loop, res was 0, thus all these
+			// power of 2 increments are now just bitsets.
+			res |= 1 << uint(bit)
 		}
 	}
 	if v >= int64(div) {