diff --git a/.github/workflows/cleanup_base.yaml b/.github/workflows/cleanup_base.yaml
index 4c36b846..6063fca0 100644
--- a/.github/workflows/cleanup_base.yaml
+++ b/.github/workflows/cleanup_base.yaml
@@ -2,7 +2,7 @@ name: Cleanup base images
 
 on:
   schedule:
-    cron: "0 3 2,16 * *" # every 2nd and 16th of the month at 3am UTC
+    - cron: "0 3 2,16 * *" # every 2nd and 16th of the month at 3am UTC
 
 jobs:
   cleanup:
diff --git a/.github/workflows/pre_build_base.yaml b/.github/workflows/pre_build_base.yaml
index 9d4dabef..3a5591a6 100644
--- a/.github/workflows/pre_build_base.yaml
+++ b/.github/workflows/pre_build_base.yaml
@@ -2,7 +2,7 @@ name: Pre-build base images
 
 on:
   schedule:
-    cron: "0 1 2,16 * *" # every 2nd and 16th of the month at 1am UTC
+    - cron: "0 1 2,16 * *" # every 2nd and 16th of the month at 1am UTC
 
 jobs:
   build_base: