diff --git a/src/gitea_codex_bot/workers/container_runner.py b/src/gitea_codex_bot/workers/container_runner.py
index 5e2c1e8..3fce7b2 100644
--- a/src/gitea_codex_bot/workers/container_runner.py
+++ b/src/gitea_codex_bot/workers/container_runner.py
@@ -26,7 +26,7 @@ logger = logging.getLogger(__name__)
 
 REVIEW_RESULT_SCHEMA: dict[str, Any] = {
     "type": "object",
-    "additionalProperties": True,
+    "additionalProperties": False,
     "required": ["verdict", "confidence", "summary", "findings", "markdown_comment"],
     "properties": {
         "verdict": {"type": "string", "enum": ["correct", "has_issues"]},
@@ -37,7 +37,7 @@ REVIEW_RESULT_SCHEMA: dict[str, Any] = {
             "type": "array",
             "items": {
                 "type": "object",
-                "additionalProperties": True,
+                "additionalProperties": False,
                 "required": ["severity", "file", "line_start", "line_end", "title", "body"],
                 "properties": {
                     "severity": {"type": "string", "enum": ["low", "medium", "high", "critical"]},