diff --git a/core/services/studio/store/storetest/contract.go b/core/services/studio/store/storetest/contract.go
index 9034a05bf2..8bc848752d 100644
--- a/core/services/studio/store/storetest/contract.go
+++ b/core/services/studio/store/storetest/contract.go
@@ -600,15 +600,18 @@ func Run(newStore New) {
 	})
 
 	It("a turn that stops beating is reaped, one that keeps beating is not", func() {
+		// The margin is wide: on a loaded runner under -race a few store calls
+		// can take longer than a tight threshold.
+		const stale = 300 * time.Millisecond
 		s := newStore()
 		chat(s, "stale", "alice")
 		chat(s, "alive", "alice")
 		Expect(s.ClaimTurn(ctx(), "alice", "stale", "r-stale")).To(Succeed())
 		Expect(s.ClaimTurn(ctx(), "alice", "alive", "r-alive")).To(Succeed())
-		time.Sleep(100 * time.Millisecond)
+		time.Sleep(2 * stale)
 		Expect(s.TouchTurn(ctx(), "alice", "alive", "r-alive")).To(Succeed())
 
-		got, err := s.ReapTurns(ctx(), 50*time.Millisecond)
+		got, err := s.ReapTurns(ctx(), stale)
 		Expect(err).NotTo(HaveOccurred())
 		Expect(got).To(HaveLen(1), "reaped = %+v, want only the chat that stopped beating", got)
 		Expect(got[0].ChatID).To(Equal("stale"))
@@ -622,7 +625,8 @@ func Run(newStore New) {
 		// The run that was reaped can no longer beat or release, and the chat is free.
 		Expect(s.TouchTurn(ctx(), "alice", "stale", "r-stale")).To(MatchError(store.ErrNotClaimed), "TouchTurn on a reaped run")
 		Expect(s.ClaimTurn(ctx(), "alice", "stale", "r-next")).To(Succeed(), "claim after reap")
-		again, _ := s.ReapTurns(ctx(), 50*time.Millisecond)
+		Expect(s.TouchTurn(ctx(), "alice", "alive", "r-alive")).To(Succeed())
+		again, _ := s.ReapTurns(ctx(), stale)
 		Expect(again).To(BeEmpty(), "a second reap found %+v", again)
 	})