diff --git a/tools/gen-stage-test-diff b/tools/gen-stage-test-diff
index fb50eaf1..c302b5e7 100755
--- a/tools/gen-stage-test-diff
+++ b/tools/gen-stage-test-diff
@@ -40,7 +40,7 @@ def run_osbuild(output_directory, store, cache_max_size, libdir, manifest):
     except subprocess.CalledProcessError as err:
         raise RuntimeError(
             f"osbuild crashed when building {manifest}:\n\nstdout:\n{err.stdout}\n\nstderr:\n{err.stderr}"
-        )
+        ) from err
 
 
 epilog = """