diff --git a/Dockerfile.mcp b/Dockerfile.mcp
index 43f5dfb..5ca7746 100644
--- a/Dockerfile.mcp
+++ b/Dockerfile.mcp
@@ -14,6 +14,7 @@ WORKDIR /app
 
 ENV UV_COMPILE_BYTECODE=1
 ENV PATH="/app/.venv/bin:$PATH"
+ENV MPLCONFIGDIR=/tmp/matplotlib
 
 COPY --from=deps /app/.venv /app/.venv
 COPY src/ src/