diff --git a/koch.nim b/koch.nim
index 92fc3a7663..253352c220 100644
--- a/koch.nim
+++ b/koch.nim
@@ -542,7 +542,7 @@ proc testUnixInstall(cmdLineRest: string) =
       execCleanPath("./koch --latest tools")
       # check the tests work:
       putEnv("NIM_EXE_NOT_IN_PATH", "NOT_IN_PATH")
-      execCleanPath("./koch tests cat megatest", destDir / "bin")
+      execCleanPath("./koch tests --nim:./bin/nim cat megatest", destDir / "bin")
     else:
       echo "Version check: failure"
   finally: