diff --git a/testament/categories.nim b/testament/categories.nim
index 17e9a48a86..0d88943cd7 100644
--- a/testament/categories.nim
+++ b/testament/categories.nim
@@ -190,8 +190,10 @@ proc ioTests(r: var TResults, cat: Category, options: string) =
 
 # ------------------------- async tests ---------------------------------------
 proc asyncTests(r: var TResults, cat: Category, options: string) =
+  # Run async with yrc instead of the default orc; the CI already runs long
+  # enough that we cannot afford to test both.
   template test(filename: untyped) =
-    testSpec r, makeTest(filename, options, cat)
+    testSpec r, makeTest(filename, options & " --mm:yrc", cat)
   for t in os.walkFiles("tests/async/t*.nim"):
     test(t)