diff --git a/dokku b/dokku
index 550d29037..b1acacf6c 100755
--- a/dokku
+++ b/dokku
@@ -73,13 +73,13 @@ case "$1" in
     do
       PROC_NAME=${line%%=*}
       PROC_COUNT=${line#*=}
-      CONTAINER_NUM=1
+      CONTAINER_INDEX=1
       oldids=$(get_container_ids $APP)
 
-      while [[ $CONTAINER_NUM -le $PROC_COUNT ]];do
-        DOKKU_CONTAINER_ID_FILE="$DOKKU_ROOT/$APP/CONTAINER.$PROC_NAME.$CONTAINER_NUM"
-        DOKKU_IP_FILE="$DOKKU_ROOT/$APP/IP.$PROC_NAME.$CONTAINER_NUM"
-        DOKKU_PORT_FILE="$DOKKU_ROOT/$APP/PORT.$PROC_NAME.$CONTAINER_NUM"
+      while [[ $CONTAINER_INDEX -le $PROC_COUNT ]];do
+        DOKKU_CONTAINER_ID_FILE="$DOKKU_ROOT/$APP/CONTAINER.$PROC_NAME.$CONTAINER_INDEX"
+        DOKKU_IP_FILE="$DOKKU_ROOT/$APP/IP.$PROC_NAME.$CONTAINER_INDEX"
+        DOKKU_PORT_FILE="$DOKKU_ROOT/$APP/PORT.$PROC_NAME.$CONTAINER_INDEX"
 
         # start the app
         DOCKER_ARGS=$(: | pluginhook docker-args $APP deploy)
@@ -121,8 +121,18 @@ case "$1" in
 
         # cleanup pre-migration files
         rm -f $DOKKU_ROOT/$APP/CONTAINER $DOKKU_ROOT/$APP/IP $DOKKU_ROOT/$APP/PORT
-        CONTAINER_NUM=$(( CONTAINER_NUM + 1 ))
+
+        CONTAINER_INDEX=$(( CONTAINER_INDEX + 1 ))
       done
+      # cleanup when we scale down
+      if [[ "$PROC_COUNT" == 0 ]]; then
+        CONTAINER_IDX_OFFSET=0
+      else
+        CONTAINER_IDX_OFFSET=$((PROC_COUNT + 1))
+      fi
+      find $DOKKU_ROOT/$APP -name "CONTAINER.$PROC_NAME.*" | tail -n +$CONTAINER_IDX_OFFSET | xargs rm -f
+      find $DOKKU_ROOT/$APP -name "IP.$PROC_NAME.*" | tail -n +$CONTAINER_IDX_OFFSET | xargs rm -f
+      find $DOKKU_ROOT/$APP -name "PORT.$PROC_NAME.*" | tail -n +$CONTAINER_IDX_OFFSET | xargs rm -f
     done < "$DOKKU_SCALE_FILE"
 
     dokku_log_info1 "Running post-deploy"
diff --git a/tests/unit/ps-buildstep.bats b/tests/unit/ps-buildstep.bats
index 1eb0d5c70..c4379af38 100644
--- a/tests/unit/ps-buildstep.bats
+++ b/tests/unit/ps-buildstep.bats
@@ -3,25 +3,26 @@
 load test_helper
 
 setup() {
-  deploy_app
+  create_app
 }
 
 teardown() {
   destroy_app
 }
 
-# @test "(ps) buildstep" {
-#   # CI support: 'Ah. I just spoke with our Docker expert --
-#   # looks like docker exec is built to work with docker-under-libcontainer,
-#   # but we're using docker-under-lxc. I don't have an estimated time for the fix, sorry
-#   skip "circleci does not support docker exec at the moment."
-#   run bash -c "dokku ps $TEST_APP | grep -q \"node web.js\""
-#   echo "output: "$output
-#   echo "status: "$status
-#   assert_success
-# }
+@test "(ps) buildstep" {
+  # CI support: 'Ah. I just spoke with our Docker expert --
+  # looks like docker exec is built to work with docker-under-libcontainer,
+  # but we're using docker-under-lxc. I don't have an estimated time for the fix, sorry
+  skip "circleci does not support docker exec at the moment."
+  run bash -c "dokku ps $TEST_APP | grep -q \"node web.js\""
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+}
 
 @test "(ps) buildstep" {
+  deploy_app
   run bash -c "dokku ps:stop $TEST_APP"
   echo "output: "$output
   echo "status: "$status
@@ -66,3 +67,52 @@ teardown() {
     assert_success
   done
 }
+
+@test "(ps:scale) buildstep" {
+  run bash -c "dokku ps:scale $TEST_APP web=2"
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+
+  deploy_app
+  CIDS=""
+  for CID_FILE in $DOKKU_ROOT/$TEST_APP/CONTAINER.web.*; do
+    CIDS+=$(< $CID_FILE)
+    CIDS+=" "
+  done
+  CIDS_PATTERN=$(echo $CIDS | sed -e "s: :|:g")
+  run bash -c "docker ps -q --no-trunc | egrep \"$CIDS_PATTERN\" | wc -l | grep 2"
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+
+  run bash -c "dokku ps:scale $TEST_APP web=1"
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+  CIDS=""
+  for CID_FILE in $DOKKU_ROOT/$TEST_APP/CONTAINER.web.*; do
+    CIDS+=$(< $CID_FILE)
+    CIDS+=" "
+  done
+  CIDS_PATTERN=$(echo $CIDS | sed -e "s: :|:g")
+  run bash -c "docker ps -q --no-trunc | egrep \"$CIDS_PATTERN\" | wc -l | grep 1"
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+
+  run bash -c "dokku ps:scale $TEST_APP web=0"
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+  CIDS=""
+  shopt -s nullglob
+  for CID_FILE in $DOKKU_ROOT/$TEST_APP/CONTAINER.web.*; do
+    CIDS+=$(< $CID_FILE)
+    CIDS+=" "
+  done
+  run bash -c "[[ -z \"$CIDS\" ]]"
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+}
diff --git a/tests/unit/ps-dockerfile.bats b/tests/unit/ps-dockerfile.bats
index bfd187982..131546525 100644
--- a/tests/unit/ps-dockerfile.bats
+++ b/tests/unit/ps-dockerfile.bats
@@ -3,25 +3,26 @@
 load test_helper
 
 setup() {
-  deploy_app dockerfile
+  create_app
 }
 
 teardown() {
   destroy_app
 }
 
-# @test "(ps) dockerfile" {
-#   # CI support: 'Ah. I just spoke with our Docker expert --
-#   # looks like docker exec is built to work with docker-under-libcontainer,
-#   # but we're using docker-under-lxc. I don't have an estimated time for the fix, sorry
-#   skip "circleci does not support docker exec at the moment."
-#   run bash -c "dokku ps $TEST_APP | grep -q \"node web.js\""
-#   echo "output: "$output
-#   echo "status: "$status
-#   assert_success
-# }
+@test "(ps) dockerfile" {
+  # CI support: 'Ah. I just spoke with our Docker expert --
+  # looks like docker exec is built to work with docker-under-libcontainer,
+  # but we're using docker-under-lxc. I don't have an estimated time for the fix, sorry
+  skip "circleci does not support docker exec at the moment."
+  run bash -c "dokku ps $TEST_APP | grep -q \"node web.js\""
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+}
 
 @test "(ps) dockerfile" {
+  deploy_app dockerfile
   run bash -c "dokku ps:stop $TEST_APP"
   echo "output: "$output
   echo "status: "$status
@@ -66,3 +67,52 @@ teardown() {
     assert_success
   done
 }
+
+@test "(ps:scale) dockerfile" {
+  run bash -c "dokku ps:scale $TEST_APP web=2"
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+
+  deploy_app dockerfile
+  CIDS=""
+  for CID_FILE in $DOKKU_ROOT/$TEST_APP/CONTAINER.web.*; do
+    CIDS+=$(< $CID_FILE)
+    CIDS+=" "
+  done
+  CIDS_PATTERN=$(echo $CIDS | sed -e "s: :|:g")
+  run bash -c "docker ps -q --no-trunc | egrep \"$CIDS_PATTERN\" | wc -l | grep 2"
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+
+  run bash -c "dokku ps:scale $TEST_APP web=1"
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+  CIDS=""
+  for CID_FILE in $DOKKU_ROOT/$TEST_APP/CONTAINER.web.*; do
+    CIDS+=$(< $CID_FILE)
+    CIDS+=" "
+  done
+  CIDS_PATTERN=$(echo $CIDS | sed -e "s: :|:g")
+  run bash -c "docker ps -q --no-trunc | egrep \"$CIDS_PATTERN\" | wc -l | grep 1"
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+
+  run bash -c "dokku ps:scale $TEST_APP web=0"
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+  CIDS=""
+  shopt -s nullglob
+  for CID_FILE in $DOKKU_ROOT/$TEST_APP/CONTAINER.web.*; do
+    CIDS+=$(< $CID_FILE)
+    CIDS+=" "
+  done
+  run bash -c "[[ -z \"$CIDS\" ]]"
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+}