diff --git a/signald-builder.Dockerfile b/signald-builder.Dockerfile
index 0fe0dc7..492b374 100644
--- a/signald-builder.Dockerfile
+++ b/signald-builder.Dockerfile
@@ -19,5 +19,5 @@ COPY deb-scripts/release-deb.sh /usr/bin/release-deb
 COPY deb-scripts/get-component.sh /usr/bin/get-component
 COPY deb-scripts/repo-cron.sh /usr/bin/repo-cron
 USER signald
-RUN add apt-signing-key.asc /tmp/apt-signing-key.asc
+ADD apt-signing-key.asc /tmp/apt-signing-key.asc
 RUN gpg --no-default-keyring --keyring trustedkeys.gpg --import /tmp/apt-signing-key.asc