diff --git a/Dockerfile b/Dockerfile
index 3e7d15b..d51078a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -21,6 +21,17 @@ RUN cd /app/custom_nodes \
     && git clone --depth 1 https://github.com/XLabs-AI/x-flux-comfyui \
     && pip install --no-cache-dir -r x-flux-comfyui/requirements.txt
 
+# Fix: xflux DoubleStreamBlock.forward must accept attn_mask kwarg passed by ComfyUI
+RUN python3 -c "
+path = '/app/custom_nodes/x-flux-comfyui/xflux/src/flux/modules/layers.py'
+with open(path) as f: c = f.read()
+old = '    def forward(self, img: Tensor, txt: Tensor, vec: Tensor, pe: Tensor) -> tuple[Tensor, Tensor]:\n      return self.processor(self, img, txt, vec, pe)'
+new = '    def forward(self, img: Tensor, txt: Tensor, vec: Tensor, pe: Tensor, attn_mask=None, transformer_options={}, **kwargs):\n      return self.processor(self, img, txt, vec, pe)'
+assert old in c, 'Pattern not found!'
+with open(path, 'w') as f: f.write(c.replace(old, new))
+print('Patch applied')
+"
+
 RUN useradd -u 1000 -m comfyui && chown -R 1000:1000 /app
 
 USER 1000