diff --git a/tests/stdlib/tthreadpool.nim b/tests/stdlib/tthreadpool.nim
new file mode 100644
index 000000000..897c7d173
--- /dev/null
+++ b/tests/stdlib/tthreadpool.nim
@@ -0,0 +1,14 @@
+discard """
+  matrix: "--threads:on --gc:arc"
+  disabled: "freebsd"
+  output: "42"
+"""
+
+from std/threadpool import spawn, `^`, sync
+block: # bug #12005
+  proc doworkok(i: int) {.thread.} = echo i
+  spawn(doworkok(42))
+  sync() # this works when returning void!
+
+  proc doworkbad(i: int): int {.thread.} = i
+  doAssert ^spawn(doworkbad(42)) == 42 # bug was here