diff --git a/core/admin/Dockerfile b/core/admin/Dockerfile
index 87676eb5..8dda76d2 100644
--- a/core/admin/Dockerfile
+++ b/core/admin/Dockerfile
@@ -23,6 +23,8 @@ RUN set -eu \
 FROM $DISTRO
 COPY --from=balenalib/rpi-alpine:3.14 /usr/bin/qemu-arm-static /usr/bin/qemu-arm-static
 
+ENV TZ Etc/UTC
+
 # python3 shared with most images
 RUN set -eu \
  && apk add --no-cache python3 py3-pip git bash tzdata \
diff --git a/core/dovecot/Dockerfile b/core/dovecot/Dockerfile
index da376d81..7a2dbdc1 100644
--- a/core/dovecot/Dockerfile
+++ b/core/dovecot/Dockerfile
@@ -11,6 +11,9 @@ RUN git clone https://github.com/grosjo/fts-xapian.git \
   && make install
 
 FROM $DISTRO
+
+ENV TZ Etc/UTC
+
 # python3 shared with most images
 RUN apk add --no-cache \
     python3 py3-pip git bash py3-multidict py3-yarl tzdata \
diff --git a/core/nginx/Dockerfile b/core/nginx/Dockerfile
index 6043cd8d..d8899144 100644
--- a/core/nginx/Dockerfile
+++ b/core/nginx/Dockerfile
@@ -1,5 +1,8 @@
 ARG DISTRO=alpine:3.14.2
 FROM $DISTRO
+
+ENV TZ Etc/UTC
+
 # python3 shared with most images
 RUN apk add --no-cache \
     python3 py3-pip git bash py3-multidict \
diff --git a/core/postfix/Dockerfile b/core/postfix/Dockerfile
index e1e1d6f9..9f0cc701 100644
--- a/core/postfix/Dockerfile
+++ b/core/postfix/Dockerfile
@@ -1,5 +1,8 @@
 ARG DISTRO=alpine:3.14.2
 FROM $DISTRO
+
+ENV TZ Etc/UTC
+
 # python3 shared with most images
 RUN apk add --no-cache \
     python3 py3-pip git bash py3-multidict py3-yarl tzdata \
diff --git a/core/rspamd/Dockerfile b/core/rspamd/Dockerfile
index 296949a2..33174c1a 100644
--- a/core/rspamd/Dockerfile
+++ b/core/rspamd/Dockerfile
@@ -1,5 +1,8 @@
 ARG DISTRO=alpine:3.14.2
 FROM $DISTRO
+
+ENV TZ Etc/UTC
+
 # python3 shared with most images
 RUN apk add --no-cache \
     python3 py3-pip git bash py3-multidict tzdata \
diff --git a/optional/clamav/Dockerfile b/optional/clamav/Dockerfile
index 7ce41453..e17d2d70 100644
--- a/optional/clamav/Dockerfile
+++ b/optional/clamav/Dockerfile
@@ -1,5 +1,8 @@
 ARG DISTRO=alpine:3.14.2
 FROM $DISTRO
+
+ENV TZ Etc/UTC
+
 # python3 shared with most images
 RUN apk add --no-cache \
     python3 py3-pip bash tzdata \
diff --git a/optional/fetchmail/Dockerfile b/optional/fetchmail/Dockerfile
index fc564a4b..995ec48f 100644
--- a/optional/fetchmail/Dockerfile
+++ b/optional/fetchmail/Dockerfile
@@ -1,6 +1,8 @@
 ARG DISTRO=alpine:3.14.2
 FROM $DISTRO
 
+ENV TZ Etc/UTC
+
 # python3 shared with most images
 RUN apk add --no-cache \
     python3 py3-pip bash tzdata \
diff --git a/optional/postgresql/Dockerfile b/optional/postgresql/Dockerfile
index ade12a24..3ddbb40a 100644
--- a/optional/postgresql/Dockerfile
+++ b/optional/postgresql/Dockerfile
@@ -1,5 +1,8 @@
 ARG DISTRO=alpine:3.14.2
 FROM $DISTRO
+
+ENV TZ Etc/UTC
+
 # python3 shared with most images
 RUN apk add --no-cache \
     python3 py3-pip bash py3-multidict tzdata \
diff --git a/optional/radicale/Dockerfile b/optional/radicale/Dockerfile
index cecaa2d3..4eb8d5a7 100644
--- a/optional/radicale/Dockerfile
+++ b/optional/radicale/Dockerfile
@@ -1,6 +1,8 @@
 ARG DISTRO=alpine:3.14.2
 FROM $DISTRO
 
+ENV TZ Etc/UTC
+
 # python3 shared with most images
 RUN apk add --no-cache \
     python3 py3-pip bash tzdata \
diff --git a/optional/traefik-certdumper/Dockerfile b/optional/traefik-certdumper/Dockerfile
index ce9b4929..506c09c2 100644
--- a/optional/traefik-certdumper/Dockerfile
+++ b/optional/traefik-certdumper/Dockerfile
@@ -1,5 +1,7 @@
 FROM ldez/traefik-certs-dumper
 
+ENV TZ Etc/UTC
+
 RUN apk --no-cache add inotify-tools util-linux bash tzdata
 
 COPY run.sh /
diff --git a/optional/unbound/Dockerfile b/optional/unbound/Dockerfile
index fde67480..bf5d4840 100644
--- a/optional/unbound/Dockerfile
+++ b/optional/unbound/Dockerfile
@@ -1,5 +1,8 @@
 ARG DISTRO=alpine:3.14.2
 FROM $DISTRO
+
+ENV TZ Etc/UTC
+
 # python3 shared with most images
 RUN apk add --no-cache \
     python3 py3-pip git bash py3-multidict tzdata \
diff --git a/webmails/rainloop/Dockerfile b/webmails/rainloop/Dockerfile
index 109546db..02910e39 100644
--- a/webmails/rainloop/Dockerfile
+++ b/webmails/rainloop/Dockerfile
@@ -4,6 +4,8 @@ ARG ARCH=""
 FROM ${ARCH}alpine:3.14
 ONBUILD COPY --from=balenalib/rpi-alpine:3.14 /usr/bin/qemu-arm-static /usr/bin/qemu-arm-static
 
+ENV TZ Etc/UTC
+
 # Shared later between dovecot postfix nginx rspamd rainloop and roundloop
 RUN apk add --no-cache \
     python3 py3-pip tzdata \
diff --git a/webmails/roundcube/Dockerfile b/webmails/roundcube/Dockerfile
index b8ba512f..f5fba3b0 100644
--- a/webmails/roundcube/Dockerfile
+++ b/webmails/roundcube/Dockerfile
@@ -7,6 +7,9 @@ ONBUILD COPY --from=balenalib/rpi-alpine:3.14 /usr/bin/qemu-arm-static /usr/bin/
 FROM ${ARCH}php:7.4-apache as build_other
 
 FROM build_${QEMU}
+
+ENV TZ Etc/UTC
+
 #Shared layer between rainloop and roundcube
 RUN apt-get update && apt-get install -y \
   python3 curl python3-pip git python3-multidict tzdata \
@@ -21,8 +24,6 @@ ENV ROUNDCUBE_URL https://github.com/roundcube/roundcubemail/releases/download/1
 
 ENV CARDDAV_URL https://github.com/mstilkerich/rcmcarddav/releases/download/v4.1.2/carddav-v4.1.2.tar.gz
 
-ENV TZ Etc/UTC
-
 RUN apt-get update && apt-get install -y \
       zlib1g-dev libzip4 libzip-dev libpq-dev \
       python3-jinja2 \