diff --git a/ot-recorder/arm/Dockerfile b/ot-recorder/arm/Dockerfile
index ccf0cd4..e4b5e72 100644
--- a/ot-recorder/arm/Dockerfile
+++ b/ot-recorder/arm/Dockerfile
@@ -7,7 +7,7 @@ MAINTAINER EasyPi Software Foundation
 
 RUN set -xe \
     && apt-get update \
-    && apt-get install -y curl \
+    && apt-get install -y curl gnupg \
     && curl -sSL http://repo.owntracks.org/repo.owntracks.org.gpg.key | apt-key add - \
     && echo 'deb http://repo.owntracks.org/debian buster main' > /etc/apt/sources.list.d/owntracks.list \
     && apt-get update \