diff --git a/Dockerfile.py b/Dockerfile.py
index f769c95..968db32 100644
--- a/Dockerfile.py
+++ b/Dockerfile.py
@@ -2,7 +2,8 @@
  
 WORKDIR /src
 RUN apt-get update && apt-get install -y build-essential g++ libgl1 libx11-6 && rm -rf /var/lib/apt/lists/*
-COPY requirements.txt .
-RUN pip install --no-cache-dir -r requirements.txt
+RUN pip install --no-cache-dir numpy pyzmq
 COPY . .
+# generated node build dirs only have a requirements.txt if the node's .dir provides one
+RUN if [ -f requirements.txt ]; then pip install --no-cache-dir -r requirements.txt; fi