diff --git a/.github/workflows/onpush_builder.yaml b/.github/workflows/onpush_builder.yaml
index 303693eed..46fba6045 100644
--- a/.github/workflows/onpush_builder.yaml
+++ b/.github/workflows/onpush_builder.yaml
@@ -167,7 +167,11 @@ jobs:
                 image=$(grep -m1 '^image:' "config.$ext" | sed 's/^image:[[:space:]]*//' | tr -d "\"'")
                 name=$(grep -m1 '^name:' "config.$ext" | sed 's/^name:[[:space:]]*//' | tr -d "\"'")
                 description=$(grep -m1 '^description:' "config.$ext" | sed 's/^description:[[:space:]]*//' | tr -d "\"'")
-                arch_list=$(sed -n '/^arch:/,/^[^ a]/p' "config.$ext" | grep '^ *-' | sed 's/^ *- *//' | tr -d "\"'" | jq -R -s -c 'split("\n") | map(select(length > 0))')
+                arch_list=$(awk '
+                  /^arch:/ { inblock=1; next }
+                  /^[^[:space:]]/ { if (inblock) exit }
+                  inblock && /^[[:space:]]/ { print }
+                ' "config.$ext" | sed 's/^ *- *//' | tr -d "\"'" | jq -R -s -c 'split("\n") | map(select(length > 0))')
               fi
               break
             fi