diff --git a/src/BatchCluster.spec.ts b/src/BatchCluster.spec.ts
index d3662f9..a2bf783 100644
--- a/src/BatchCluster.spec.ts
+++ b/src/BatchCluster.spec.ts
@@ -444,7 +444,7 @@ describe("BatchCluster", function () {
                       expect(bc.pids()).to.not.include.members(pids)
 
                     expect(bc.meanTasksPerProc).to.be.within(
-                      0.25, // because flaky
+                      0.15, // because flaky (macOS on GHA resulted in 0.21) 
                       opts.maxTasksPerProcess,
                     )
                     expect(bc.pids().length).to.be.lte(maxProcs)