diff --git a/ci/set_versions.py b/ci/set_versions.py
index 147c7a1bc3..f5417b38e6 100644
--- a/ci/set_versions.py
+++ b/ci/set_versions.py
@@ -4,4 +4,4 @@
 
 versions = json.loads(versions)
 
-print(json.dumps([{"rust-version": version, "target-versions": versions[0:i+1] } for (i, version) in enumerate(versions)]))
+print(json.dumps([{"rust-version": version, "target-versions": json.dumps(versions[0:i+1]) } for (i, version) in enumerate(versions)]))