diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index b6a0559fb..dd35cc33d 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -2,6 +2,9 @@ name: C/C++ CI
 
 on: [push, pull_request]
 
+env:
+  CTEST_PARALLEL_LEVEL: "1"
+
 jobs:
   ubuntu: