diff --git a/worker/Dockerfile b/worker/Dockerfile
index d3e5068..ebe5e49 100644
--- a/worker/Dockerfile
+++ b/worker/Dockerfile
@@ -1,4 +1,7 @@
-FROM rust:1.97 AS build
+# Pinned to -bookworm to match the bookworm-slim runtime stage below — the plain `rust:1.97` tag
+# now resolves to a trixie base, whose newer glibc produced binaries the runtime's older glibc
+# couldn't load ("GLIBC_2.38 not found"), confirmed by actually running the built image.
+FROM rust:1.97-bookworm AS build
 WORKDIR /app
 COPY . .
 RUN cargo build --release