diff --git a/Dockerfile b/Dockerfile
index 1e89e79..a947fdb 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -21,9 +21,6 @@ RUN go mod download
 FROM golang:alpine AS builder
 ARG CONF_NUM
 
-# Fail fast if CONF_NUM missing
-RUN test -n "$CONF_NUM"
-
 RUN apk add --no-cache git
 
 WORKDIR /oc-discovery
@@ -55,13 +52,13 @@ WORKDIR /app
 
 RUN mkdir ./pem
 
-COPY --from=builder /app/extracted/pem/private${CONF_NUM}.pem ./pem/private.pem
+COPY --from=builder /app/extracted/pem/private${CONF_NUM:-1}.pem ./pem/private.pem
 COPY --from=builder /app/extracted/psk ./psk
-COPY --from=builder /app/extracted/pem/public${CONF_NUM}.pem ./pem/public.pem
+COPY --from=builder /app/extracted/pem/public${CONF_NUM:-1}.pem ./pem/public.pem
 
 COPY --from=builder /app/extracted/oc-discovery /usr/bin/oc-discovery
-COPY --from=builder /app/extracted/docker_discovery${CONF_NUM}.json /etc/oc/discovery.json
+COPY --from=builder /app/extracted/docker_discovery${CONF_NUM:-1}.json /etc/oc/discovery.json
 
-EXPOSE 400${CONF_NUM}
+EXPOSE 400${CONF_NUM:-1}
 
 ENTRYPOINT ["oc-discovery"]
\ No newline at end of file