diff --git a/buildkite/clone_repositories.sh b/buildkite/clone_repositories.sh
index 86cbf371..c91f7df0 100755
--- a/buildkite/clone_repositories.sh
+++ b/buildkite/clone_repositories.sh
@@ -47,5 +47,5 @@ done
 
 for dir in dmd druntime phobos ; do
     echo "--- Building $dir"
-    make -C $dir -f posix.mak AUTO_BOOTSTRAP=1 --jobs=4
+    make -C $dir -f posix.mak AUTO_BOOTSTRAP=1 --jobs=4 BUILD=debug
 done