diff --git a/rust2rpm/__main__.py b/rust2rpm/__main__.py
index 61697a7..f989986 100644
--- a/rust2rpm/__main__.py
+++ b/rust2rpm/__main__.py
@@ -8,7 +8,7 @@ from cargo2rpm.semver import Version
 from rust2rpm import log
 from rust2rpm.cli import get_parser
 from rust2rpm.conf import load_config
-from rust2rpm.crate import process_project
+from rust2rpm.crate import InvalidRequestError, process_project
 from rust2rpm.cratesio import NoVersionsError
 from rust2rpm.distgit import get_package_info
 from rust2rpm.generator import spec_render_crate, spec_render_project, spec_render_workspace
@@ -53,6 +53,9 @@ def main():
     except NoVersionsError:
         log.error(f"No versions are available for crate {args.crate!r}.")
         sys.exit(1)
+    except InvalidRequestError as exc:
+        log.error(str(exc))
+        sys.exit(1)
 
     if metadata.is_workspace():
         base_name = project
diff --git a/rust2rpm/crate.py b/rust2rpm/crate.py
index 07f4df7..dbc15f7 100644
--- a/rust2rpm/crate.py
+++ b/rust2rpm/crate.py
@@ -54,6 +54,10 @@ DOC_FILE_PATTERN = re.compile(
 DOC_FILE_EXCLUDES = re.compile(r"CMakeLists\.txt|versions\.txt|.*\.tpl|.*\.in")
 
 
+class InvalidRequestError(ValueError):
+    pass
+
+
 def local_toml_file(toml_path: str) -> tuple[str, list[str], list[str]]:
     assert os.path.isfile(toml_path)
     assert os.path.basename(toml_path) == "Cargo.toml"
@@ -256,7 +260,7 @@ def process_project(
     if project_is_path(project) and not project.endswith(".crate"):
         # project points into unpacked sources:
         if store_crate:
-            raise ValueError("The '--store-crate' / '-s' flag cannot be used for unpacked sources.")
+            raise InvalidRequestError("The '--store-crate' / '-s' flag cannot be used for unpacked sources.")
 
         # process unpacked sources
         name, version, diffs, metadata, doc_files, license_files, vendor_tarball = process_project_local(