diff --git a/Dockerfile.m4 b/Dockerfile.m4
index 125a1a7..7d5ea04 100644
--- a/Dockerfile.m4
+++ b/Dockerfile.m4
@@ -14,6 +14,10 @@ RUN <<-EOF
 	sed -i '/^Components: main$/s/$/ contrib non-free non-free-firmware/' /etc/apt/sources.list.d/debian.sources
 EOF
 
+RUN <<-EOF
+	sed -i '/^Components: main$/s/$/ contrib non-free non-free-firmware/' /etc/apt/sources.list.d/debian.sources
+EOF
+
 # Install packages
 RUN <<-EOF
 	export DEBIAN_FRONTEND=noninteractive