diff --git a/tools/test-case-generators/generate-test-cases b/tools/test-case-generators/generate-test-cases
index 38c802dc1..eed278fa6 100755
--- a/tools/test-case-generators/generate-test-cases
+++ b/tools/test-case-generators/generate-test-cases
@@ -30,6 +30,7 @@ def run_osbuild(manifest, store, output):
                             encoding="utf-8",
                             input=json.dumps(manifest))
         except:
+            log.seek(0)
             print(log.read())
             raise