diff --git a/container/Containerfile b/container/Containerfile
index 1632a08e..1e5b62ca 100644
--- a/container/Containerfile
+++ b/container/Containerfile
@@ -32,7 +32,9 @@ RUN curl -fsSL https://deb.nodesource.com/setup_${NODE_MAJOR}.x | bash - \
     && rm -rf /var/lib/apt/lists/*
 
 # REUSE >= 3 (Debian's packaged reuse is too old for REUSE.toml).
-RUN PIPX_HOME=/opt/pipx PIPX_BIN_DIR=/usr/local/bin pipx install reuse
+# The [charset-normalizer] extra provides an encoding-detection backend;
+# without it (and without libmagic) reuse fails to import at runtime.
+RUN PIPX_HOME=/opt/pipx PIPX_BIN_DIR=/usr/local/bin pipx install 'reuse[charset-normalizer]'
 
 # Rust stable with rustfmt + clippy, installed system-wide.
 RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs \