diff --git a/src/net/timeout_test.go b/src/net/timeout_test.go
index 3c6aa27cc1..d1cfbf853c 100644
--- a/src/net/timeout_test.go
+++ b/src/net/timeout_test.go
@@ -644,10 +644,20 @@ const (
 // timeoutUpperBound returns the maximum time that we expect a timeout of
 // duration d to take to return the caller.
 func timeoutUpperBound(d time.Duration) time.Duration {
-	// In https://storage.googleapis.com/go-build-log/1e637cd3/openbsd-amd64-68_3585d3e7.log,
-	// we observed that an openbsd-amd64-68 builder took 636ms for a 512ms timeout
-	// (24.2% overhead).
-	return d * 4 / 3
+	switch runtime.GOOS {
+	case "openbsd", "netbsd":
+		// NetBSD and OpenBSD seem to be unable to reliably hit deadlines even when
+		// the absolute durations are long.
+		// In https://build.golang.org/log/c34f8685d020b98377dd4988cd38f0c5bd72267e,
+		// we observed that an openbsd-amd64-68 builder took 4.090948779s for a
+		// 2.983020682s timeout (37.1% overhead).
+		// (See https://go.dev/issue/50189 for further detail.)
+		// Give them lots of slop to compensate.
+		return d * 3 / 2
+	}
+	// Other platforms seem to hit their deadlines more reliably,
+	// at least when they are long enough to cover scheduling jitter.
+	return d * 11 / 10
 }
 
 // nextTimeout returns the next timeout to try after an operation took the given