diff --git a/Dockerfile.backend b/Dockerfile.backend
index 49cf313..3bd6b3d 100644
--- a/Dockerfile.backend
+++ b/Dockerfile.backend
@@ -48,6 +48,7 @@ FROM ldns AS engine-build
 
 RUN apk add --no-cache \
     gcc \
+    gettext \
     make \
     musl-dev \
     perl-dev \
@@ -82,6 +83,7 @@ RUN apk add --no-cache \
     Locale::PO \
     Locale::TextDomain \
     Module::Find \
+    Net::DNS \
     Net::IP::XS
 
 COPY zonemaster-engine/ /src/engine/