diff --git a/scripts/make.fsx b/scripts/make.fsx
index 64a94a4e4..03cec75e9 100755
--- a/scripts/make.fsx
+++ b/scripts/make.fsx
@@ -433,8 +433,17 @@ match maybeTarget with
             }
 #endif
 
-    Process.Execute(runnerCommand, Echo.All).UnwrapDefault()
+    let procResult = Process.Execute(runnerCommand, Echo.All)
+#if !LEGACY_FRAMEWORK
+    procResult.UnwrapDefault()
     |> ignore<string>
+#else // in legacy mode, warnings (output to StdErr) happen even if exitCode=0
+    match procResult.Result with
+    | ProcessResultState.Error (_, _) ->
+        failwith "Unit tests failed ^"
+    | _ ->
+        ()
+#endif
 
 | Some("install") ->
     let buildConfig = BinaryConfig.Release