diff --git a/src/math/big/natconv.go b/src/math/big/natconv.go
index e216bd288cc..44547842c1c 100644
--- a/src/math/big/natconv.go
+++ b/src/math/big/natconv.go
@@ -391,7 +391,7 @@ func (q nat) convertWords(s []byte, b Word, ndigits int, bb Word, table []diviso
 				// this appears to be faster for BenchmarkString10000Base10
 				// and smaller strings (but a bit slower for larger ones)
 				t := r / 10
-				s[i] = '0' + byte(r-t<<3-t-t) // TODO(gri) replace w/ t*10 once compiler produces better code
+				s[i] = '0' + byte(r-t*10)
 				r = t
 			}
 		}