diff --git a/11.0/Dockerfile b/11.0/Dockerfile
index 640224a..015fbf2 100644
--- a/11.0/Dockerfile
+++ b/11.0/Dockerfile
@@ -39,7 +39,8 @@ RUN apt-get update \
 
 # install latest postgresql-client
 RUN echo 'deb http://apt.postgresql.org/pub/repos/apt/ stretch-pgdg main' > /etc/apt/sources.list.d/pgdg.list \
-        && export GNUPGHOME="$(mktemp -d)" \
+        && GNUPGHOME="$(mktemp -d)" \
+        && export GNUPGHOME \
         && repokey='B97B0AFCAA1A47F044F244A07FCC7D46ACCC4CF8' \
         && gpg --batch --keyserver keyserver.ubuntu.com --recv-keys "${repokey}" \
         && gpg --batch --armor --export "${repokey}" > /etc/apt/trusted.gpg.d/pgdg.gpg.asc \
diff --git a/12.0/Dockerfile b/12.0/Dockerfile
index 887762f..791890b 100644
--- a/12.0/Dockerfile
+++ b/12.0/Dockerfile
@@ -39,7 +39,8 @@ RUN apt-get update \
 
 # install latest postgresql-client
 RUN echo 'deb http://apt.postgresql.org/pub/repos/apt/ stretch-pgdg main' > /etc/apt/sources.list.d/pgdg.list \
-        && export GNUPGHOME="$(mktemp -d)" \
+        && GNUPGHOME="$(mktemp -d)" \
+        && export GNUPGHOME \
         && repokey='B97B0AFCAA1A47F044F244A07FCC7D46ACCC4CF8' \
         && gpg --batch --keyserver keyserver.ubuntu.com --recv-keys "${repokey}" \
         && gpg --batch --armor --export "${repokey}" > /etc/apt/trusted.gpg.d/pgdg.gpg.asc \
@@ -51,7 +52,8 @@ RUN echo 'deb http://apt.postgresql.org/pub/repos/apt/ stretch-pgdg main' > /etc
 
 # Install rtlcss (on Debian stretch)
 RUN echo "deb http://deb.nodesource.com/node_8.x stretch main" > /etc/apt/sources.list.d/nodesource.list \
-    && export GNUPGHOME="$(mktemp -d)" \
+    && GNUPGHOME="$(mktemp -d)" \
+    && export GNUPGHOME \
     && repokey='9FD3B784BC1C6FC31A8A0A1C1655A0AB68576280' \
     && gpg --batch --keyserver keyserver.ubuntu.com --recv-keys "${repokey}" \
     && gpg --batch --armor --export "${repokey}" > /etc/apt/trusted.gpg.d/nodejs.gpg.asc \
diff --git a/13.0/Dockerfile b/13.0/Dockerfile
index b1bb1f5..9213acd 100644
--- a/13.0/Dockerfile
+++ b/13.0/Dockerfile
@@ -37,7 +37,8 @@ RUN apt-get update \
 
 # install latest postgresql-client
 RUN echo 'deb http://apt.postgresql.org/pub/repos/apt/ buster-pgdg main' > /etc/apt/sources.list.d/pgdg.list \
-        && export GNUPGHOME="$(mktemp -d)" \
+        && GNUPGHOME="$(mktemp -d)" \
+        && export GNUPGHOME \
         && repokey='B97B0AFCAA1A47F044F244A07FCC7D46ACCC4CF8' \
         && gpg --batch --keyserver keyserver.ubuntu.com --recv-keys "${repokey}" \
         && gpg --batch --armor --export "${repokey}" > /etc/apt/trusted.gpg.d/pgdg.gpg.asc \