diff --git a/src/testing/benchmark.go b/src/testing/benchmark.go
index dbc0814884..78e1b2de6d 100644
--- a/src/testing/benchmark.go
+++ b/src/testing/benchmark.go
@@ -275,6 +275,11 @@ func (b *B) doBench() BenchmarkResult {
 }
 
 func predictN(goalns int64, prevIters int64, prevns int64, last int64) int {
+	if prevns == 0 {
+		// Round up to dodge divide by zero. See https://go.dev/issue/70709.
+		prevns = 1
+	}
+
 	// Order of operations matters.
 	// For very fast benchmarks, prevIters ~= prevns.
 	// If you divide first, you get 0 or 1,
@@ -321,12 +326,7 @@ func (b *B) launch() {
 				// Predict required iterations.
 				goalns := d.Nanoseconds()
 				prevIters := int64(b.N)
-				prevns := b.duration.Nanoseconds()
-				if prevns <= 0 {
-					// Round up, to avoid div by zero.
-					prevns = 1
-				}
-				n = int64(predictN(goalns, prevIters, prevns, last))
+				n = int64(predictN(goalns, prevIters, b.duration.Nanoseconds(), last))
 				b.runN(int(n))
 			}
 		}