diff --git a/src/test/kotlin/de/hoennig/werkator/build/BuildExecutorTest.kt b/src/test/kotlin/de/hoennig/werkator/build/BuildExecutorTest.kt
index 1174a1f..cb6a0a9 100644
--- a/src/test/kotlin/de/hoennig/werkator/build/BuildExecutorTest.kt
+++ b/src/test/kotlin/de/hoennig/werkator/build/BuildExecutorTest.kt
@@ -505,6 +505,8 @@ class BuildExecutorTest : FunSpec() {
         }
 
         test("with maxConcurrent 1 a second branch stays PENDING until the first finished") {
+            // branch-a blocks on a gate file the test creates, so the PENDING assertion
+            // below cannot race the first build finishing on a loaded machine
             val h =
                 Harness(
                     """
@@ -512,7 +514,7 @@ class BuildExecutorTest : FunSpec() {
                       maxConcurrent: 1
                     branches:
                       branch-a:
-                        buildCommand: "sleep 1"
+                        buildCommand: "until [ -f gate ]; do sleep 0.05; done"
                         cleanCommand: ""
                       branch-b:
                         buildCommand: "echo ok"
@@ -523,8 +525,13 @@ class BuildExecutorTest : FunSpec() {
             h.executor.startBuild(h.repo, "branch-a", "sha-a")
             h.executor.startBuild(h.repo, "branch-b", "sha-b")
 
+            eventually(30.seconds) {
+                h.repository.latestFor("branch-a")?.status shouldBe BuildStatus.RUNNING
+            }
             h.repository.latestFor("branch-b")?.status shouldBe BuildStatus.PENDING
 
+            Files.createFile(h.workingDir.resolve("gate"))
+
             awaitStatus(h, "branch-b", BuildStatus.SUCCESS)
             awaitStatus(h, "branch-a", BuildStatus.SUCCESS)
             val transitions = h.events.map { it.result.branch to it.result.status }