diff --git a/scripts/build.py b/scripts/build.py
index c866ba033a3c5bc1791fbed717dd1e3293e0ce70..c59e2d8494e927c09c0770f843070fc5764ac9ee 100755
--- a/scripts/build.py
+++ b/scripts/build.py
@@ -63,19 +63,21 @@ def build_package(repo_dir, package_dir, name,
                 "Extracted package {} is not expected package {}".format(
                     pkg_name, name))
 
+        print("Extracted name", pkg_dir, pkg_name)
+
         workdir = os.path.join(tempdir, pkg_dir)
-        os.chdir(workdir)
 
-        print(os.listdir())
+        print("Content of tempdir:", os.listdir(workdir))
+        print("Content of workdir:", os.listdir(workdir))
 
         if additional_content is not None:
             print("applying additional content")
             os.chdir(workdir)
-            print(os.listdir())
             for content in additional_content:
-                print("applying {}".format(content))
-                os.chdir(content["target_dir"])
-                print(os.listdir())
+                target_dir = content["target_dir"]
+                print("applying", content, "in", target_dir)
+                os.listdir(target_dir)
+                os.chdir(target_dir)
                 if "patch_dir" in content:
                     abs_patch_dir = os.path.join(
                         repo_dir, content["patch_dir"])
@@ -83,10 +85,11 @@ def build_package(repo_dir, package_dir, name,
                 elif "git_url" in content:
                     run_checked(["git", "clone", content["git_url"]])
                 else:
-                    print(
+                    raise ValueError(
                         "Unknown kind of additional content: {}".format(
                             content))
 
+        os.chdir(workdir)
 
         command = ["debchange", "--preserve"]
         if version is None: