diff --git a/9.0/Dockerfile b/9.0/Dockerfile
index 402d06a64c..7afa3d3833 100644
--- a/9.0/Dockerfile
+++ b/9.0/Dockerfile
@@ -1,8 +1,8 @@
 # vim:set ft=dockerfile:
 FROM debian:jessie
 
-# add our user and group first to make sure their IDs get assigned consistently, regardless of whatever dependencies get added
-RUN groupadd -r postgres && useradd -r -g postgres postgres
+# explicitly set user/group IDs
+RUN groupadd -r postgres --gid=999 && useradd -r -g postgres --uid=999 postgres
 
 # grab gosu for easy step-down from root
 RUN gpg --keyserver pool.sks-keyservers.net --recv-keys B42F6819007F00F88E364FD4036A9C25BF357DD4
diff --git a/9.1/Dockerfile b/9.1/Dockerfile
index 47c28da8ab..4b3d1618a6 100644
--- a/9.1/Dockerfile
+++ b/9.1/Dockerfile
@@ -1,8 +1,8 @@
 # vim:set ft=dockerfile:
 FROM debian:jessie
 
-# add our user and group first to make sure their IDs get assigned consistently, regardless of whatever dependencies get added
-RUN groupadd -r postgres && useradd -r -g postgres postgres
+# explicitly set user/group IDs
+RUN groupadd -r postgres --gid=999 && useradd -r -g postgres --uid=999 postgres
 
 # grab gosu for easy step-down from root
 RUN gpg --keyserver pool.sks-keyservers.net --recv-keys B42F6819007F00F88E364FD4036A9C25BF357DD4
diff --git a/9.2/Dockerfile b/9.2/Dockerfile
index c53abfffe0..b2e0f26733 100644
--- a/9.2/Dockerfile
+++ b/9.2/Dockerfile
@@ -1,8 +1,8 @@
 # vim:set ft=dockerfile:
 FROM debian:jessie
 
-# add our user and group first to make sure their IDs get assigned consistently, regardless of whatever dependencies get added
-RUN groupadd -r postgres && useradd -r -g postgres postgres
+# explicitly set user/group IDs
+RUN groupadd -r postgres --gid=999 && useradd -r -g postgres --uid=999 postgres
 
 # grab gosu for easy step-down from root
 RUN gpg --keyserver pool.sks-keyservers.net --recv-keys B42F6819007F00F88E364FD4036A9C25BF357DD4
diff --git a/9.3/Dockerfile b/9.3/Dockerfile
index 0da54998bc..23eb1a23d9 100644
--- a/9.3/Dockerfile
+++ b/9.3/Dockerfile
@@ -1,8 +1,8 @@
 # vim:set ft=dockerfile:
 FROM debian:jessie
 
-# add our user and group first to make sure their IDs get assigned consistently, regardless of whatever dependencies get added
-RUN groupadd -r postgres && useradd -r -g postgres postgres
+# explicitly set user/group IDs
+RUN groupadd -r postgres --gid=999 && useradd -r -g postgres --uid=999 postgres
 
 # grab gosu for easy step-down from root
 RUN gpg --keyserver pool.sks-keyservers.net --recv-keys B42F6819007F00F88E364FD4036A9C25BF357DD4
diff --git a/9.4/Dockerfile b/9.4/Dockerfile
index ab89a77d32..9de3523a6c 100644
--- a/9.4/Dockerfile
+++ b/9.4/Dockerfile
@@ -1,8 +1,8 @@
 # vim:set ft=dockerfile:
 FROM debian:jessie
 
-# add our user and group first to make sure their IDs get assigned consistently, regardless of whatever dependencies get added
-RUN groupadd -r postgres && useradd -r -g postgres postgres
+# explicitly set user/group IDs
+RUN groupadd -r postgres --gid=999 && useradd -r -g postgres --uid=999 postgres
 
 # grab gosu for easy step-down from root
 RUN gpg --keyserver pool.sks-keyservers.net --recv-keys B42F6819007F00F88E364FD4036A9C25BF357DD4
diff --git a/9.5/Dockerfile b/9.5/Dockerfile
index 44142b8295..9d9ab9c822 100644
--- a/9.5/Dockerfile
+++ b/9.5/Dockerfile
@@ -1,8 +1,8 @@
 # vim:set ft=dockerfile:
 FROM debian:jessie
 
-# add our user and group first to make sure their IDs get assigned consistently, regardless of whatever dependencies get added
-RUN groupadd -r postgres && useradd -r -g postgres postgres
+# explicitly set user/group IDs
+RUN groupadd -r postgres --gid=999 && useradd -r -g postgres --uid=999 postgres
 
 # grab gosu for easy step-down from root
 RUN gpg --keyserver pool.sks-keyservers.net --recv-keys B42F6819007F00F88E364FD4036A9C25BF357DD4