diff --git a/Dockerfile b/Dockerfile
index 0da46f33a9..c9219d51a7 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -14,9 +14,11 @@ ARG RUST_TOOLCHAIN="1.66.0"
 WORKDIR /tmp
 
 # NB: pkg-config and libssl are for container TLS; we may switch to rustls in the future.
+# NB: cmake is required for freetype-sys-0.13.1, which in turn has only been added for imgui/egui.
 RUN apt-get update \
     && DEBIAN_FRONTEND=noninteractive TZ=Etc/UTC apt-get install -y \
         build-essential \
+        cmake \
         curl \
         libssl-dev \
         pkg-config