diff --git a/rust2rpm/__main__.py b/rust2rpm/__main__.py
index d7df115..379013a 100644
--- a/rust2rpm/__main__.py
+++ b/rust2rpm/__main__.py
@@ -2,7 +2,7 @@ import os
 import pathlib
 import sys
 
-from cargo2rpm.metadata import FeatureFlags
+from cargo2rpm.metadata import FeatureFlags, Version
 
 from rust2rpm import log
 from rust2rpm.cli import get_parser
@@ -113,7 +113,14 @@ def main():
         )
 
     if not metadata.is_workspace():
-        warn_if_package_uses_restrictive_dependencies(metadata.packages[0])
+        package = metadata.packages[0]
+
+        if build_meta := Version.parse(package.version).build:
+            log.error(f"Crate version {package.version!r} contains build metadata: '+{build_meta}'")
+            log.error(f"This is not supported by rust2rpm; remove the '+{build_meta}' suffix.")
+            sys.exit(1)
+
+        warn_if_package_uses_restrictive_dependencies(package)
 
         spec_contents = spec_render_crate(
             metadata=metadata,