diff --git a/.github/workflows/weekly.yml b/.github/workflows/weekly.yml
index 865cc46..7245547 100644
--- a/.github/workflows/weekly.yml
+++ b/.github/workflows/weekly.yml
@@ -25,6 +25,22 @@ jobs:
         run: test "$(git tag --points-at HEAD)" = ""
 
       - name: Build base
+        run: |
+          set -ex
+
+          case "${{matrix.target_arch}}" in \
+            riscv64) \
+              JINX_CONFIG_FILE=jinx-config-riscv64 ./jinx build base ;; \
+            x86_64) \
+              ./jinx build base ;; \
+          esac
+
+      - name: Remove leftovers to reduce space
+        run: |
+          set -ex
+          rm -rf sources builds host-builds
+
+      - name: Build image
         run: |
           set -ex