diff --git a/cubbi/images/opencode/Dockerfile b/cubbi/images/opencode/Dockerfile
index 6875e22..e447f52 100644
--- a/cubbi/images/opencode/Dockerfile
+++ b/cubbi/images/opencode/Dockerfile
@@ -67,6 +67,7 @@ RUN echo '[ -x /cubbi/init-status.sh ] && /cubbi/init-status.sh' >> /etc/bash.ba
 ENV PYTHONUNBUFFERED=1
 ENV PYTHONDONTWRITEBYTECODE=1
 ENV UV_LINK_MODE=copy
+ENV COLORTERM=truecolor
 
 # Pre-install the cubbi_init
 RUN /cubbi/cubbi_init.py --help
diff --git a/cubbi/images/opencode/opencode_plugin.py b/cubbi/images/opencode/opencode_plugin.py
index 20bcde0..69b65ee 100644
--- a/cubbi/images/opencode/opencode_plugin.py
+++ b/cubbi/images/opencode/opencode_plugin.py
@@ -182,6 +182,9 @@ class OpencodePlugin(ToolPlugin):
         else:
             config_data = {}
 
+        # Set default theme to system
+        config_data.setdefault("theme", "system")
+
         # Update with environment variables
         opencode_model = os.environ.get("CUBBI_MODEL")
         opencode_provider = os.environ.get("CUBBI_PROVIDER")