diff --git a/build.sbt b/build.sbt
index 035edbb68cc..394aefa10cd 100644
--- a/build.sbt
+++ b/build.sbt
@@ -227,8 +227,14 @@ lazy val FileService = (project in file("file-service"))
     Test / fork := true,
     Test / forkOptions := (Test / forkOptions).value
       .withWorkingDirectory((ThisBuild / baseDirectory).value),
-    Test / testGrouping := (Test / definedTests).value.map { suite =>
-      Tests.Group(suite.name, Seq(suite), Tests.SubProcess((Test / forkOptions).value))
+    Test / testGrouping := {
+      // Read once, outside the loop: sbt lifts a `.value` written inside a lambda to
+      // the top of the task anyway, so leaving it there reads as one lookup per suite
+      // when it is not, and sbt warns about exactly that.
+      val forked = (Test / forkOptions).value
+      (Test / definedTests).value.map { suite =>
+        Tests.Group(suite.name, Seq(suite), Tests.SubProcess(forked))
+      }
     }
   )