diff --git a/src/Nocr.TelegramClient.Host/Dockerfile b/src/Nocr.TelegramClient.Host/Dockerfile
index fe1b51c..4e24dd4 100644
--- a/src/Nocr.TelegramClient.Host/Dockerfile
+++ b/src/Nocr.TelegramClient.Host/Dockerfile
@@ -16,8 +16,11 @@ RUN apt-get update && \
     update-ca-certificates && \
     rm -rf /var/lib/apt/lists/*
 
-# Copy nuget.config from parent repository (via additional_contexts)
-COPY --from=rootconfig nuget.config /root/.nuget/NuGet/NuGet.Config
+# Copy nuget.config from build context root
+# Must be copied to submodule root before building:
+# - CI: pipeline copies it with "cp nuget.config telegram-client/"
+# - Docker Compose: run ./prepare-build.sh first
+COPY nuget.config /root/.nuget/NuGet/NuGet.Config
 
 COPY . .