diff --git a/internal/davsync/stall_test.go b/internal/davsync/stall_test.go
index c2713c10..e9b26863 100644
--- a/internal/davsync/stall_test.go
+++ b/internal/davsync/stall_test.go
@@ -152,7 +152,11 @@ func narrow(c net.Conn, buffer int) error {
 // down, but never stops moving, is written and read in full (#657: 43 MB
 // at 305 KB/s took 2.4 minutes, and a sync was given 2).
 func TestSlowTransferIsNotCutShort(t *testing.T) {
-	shortStall(t, 300*time.Millisecond, 300*time.Millisecond)
+	// a second, not the 300 ms the other stall tests use: a macOS runner
+	// can stop the whole test for a few hundred ms, and here the line never
+	// stops, so such a pause is all a shorter watchdog would catch (red
+	// on macOS in run 37693090857, near the end of the GET)
+	shortStall(t, time.Second, time.Second)
 	// the PUT's last MBs cross the line twice the watchdog after magpie has
 	// handed them all over
 	s := &slowDAV{chunk: 256 << 10, gap: 40 * time.Millisecond, tail: 2 * stallAfter}
@@ -162,8 +166,8 @@ func TestSlowTransferIsNotCutShort(t *testing.T) {
 		t.Fatal(err)
 	}
 	d.client = client
-	// ~20 MB at 6.4 MB/s: 3 s each way
-	data := bytes.Repeat([]byte("magpie skill "), (20<<20)/13)
+	// ~24 MB at 6.4 MB/s: nearly 4 s each way
+	data := bytes.Repeat([]byte("magpie skill "), (24<<20)/13)
 	ctx := context.Background()
 	start := time.Now()
 	if _, err := d.put(ctx, data, ""); err != nil {
@@ -179,7 +183,7 @@ func TestSlowTransferIsNotCutShort(t *testing.T) {
 	if !bytes.Equal(got, data) {
 		t.Fatalf("read back %d bytes of %d", len(got), len(data))
 	}
-	if up < 5*stallAfter || down < 5*stallAfter {
+	if up < 3*stallAfter || down < 3*stallAfter {
 		t.Fatalf("the transfers (%s up, %s down) weren't slow enough to test anything", up, down)
 	}
 }