diff --git a/plugins/app-json/internal-functions b/plugins/app-json/internal-functions
index cdb8ff68c..8c113137b 100755
--- a/plugins/app-json/internal-functions
+++ b/plugins/app-json/internal-functions
@@ -86,7 +86,7 @@ execute_script() {
   local DOCKER_ARGS=$(sed -e "s/--restart=[[:graph:]]\+[[:blank:]]\?//g" <<<"$DOCKER_ARGS")
 
   local IMAGE_SOURCE_TYPE="dockerfile"
-  is_image_herokuish_based "$IMAGE" && IMAGE_SOURCE_TYPE="herokuish"
+  is_image_herokuish_based "$IMAGE" "$APP" && IMAGE_SOURCE_TYPE="herokuish"
   DOCKER_ARGS+=$(: | plugn trigger docker-args-process-deploy "$APP" "$IMAGE_TAG" "$IMAGE_SOURCE_TYPE")
 
   # eval args as array to respect escapes
@@ -109,7 +109,7 @@ execute_script() {
     return
   fi
 
-  if ! is_image_herokuish_based "$IMAGE"; then
+  if ! is_image_herokuish_based "$IMAGE" "$APP"; then
     local DOKKU_DOCKERFILE_ENTRYPOINT=$(config_get "$APP" DOKKU_DOCKERFILE_ENTRYPOINT)
     local DOKKU_DOCKERFILE_CMD=$(config_get "$APP" DOKKU_DOCKERFILE_CMD)
     [[ -z "$DOKKU_DOCKERFILE_ENTRYPOINT" ]] && DOKKU_DOCKERFILE_ENTRYPOINT="$(get_entrypoint_from_image "$IMAGE")"
diff --git a/plugins/checks/subcommands/run b/plugins/checks/subcommands/run
index bd14b66af..892268cbf 100755
--- a/plugins/checks/subcommands/run
+++ b/plugins/checks/subcommands/run
@@ -58,7 +58,7 @@ check_process() {
 
   IS_HEROKUISH_CONTAINER=false
   IMAGE=$(get_app_image_name "$APP")
-  is_image_herokuish_based "$IMAGE" && IS_HEROKUISH_CONTAINER=true
+  is_image_herokuish_based "$IMAGE" "$APP" && IS_HEROKUISH_CONTAINER=true
 
   dokku_log_info1 "Running checks for app ($APP.$PROC_TYPE.$CONTAINER_INDEX)"
   CONTAINER_ID=$(<"$DOKKU_CONTAINER_ID_FILE")
diff --git a/plugins/common/common.go b/plugins/common/common.go
index 23038b960..3d62fddab 100644
--- a/plugins/common/common.go
+++ b/plugins/common/common.go
@@ -245,7 +245,7 @@ func IsDeployed(appName string) bool {
 }
 
 // IsImageHerokuishBased returns true if app image is based on herokuish
-func IsImageHerokuishBased(image string) bool {
+func IsImageHerokuishBased(image string, appName string) bool {
 	output, err := DockerInspect(image, "{{range .Config.Env}}{{if eq . \"USER=herokuishuser\" }}{{println .}}{{end}}{{end}}")
 	if err != nil {
 		return false
diff --git a/plugins/common/functions b/plugins/common/functions
index 66cf890ae..9fbd0abf0 100755
--- a/plugins/common/functions
+++ b/plugins/common/functions
@@ -293,14 +293,20 @@ get_running_image_tag() {
 is_image_herokuish_based() {
   declare desc="returns true if app image is based on herokuish"
   declare IMAGE="$1"
+  declare APP="$2"
+  local DOKKU_APP_USER
+  if [[ -n "$APP" ]]; then
+    DOKKU_APP_USER=$(config_get "$APP" DOKKU_APP_USER || true)
+  fi
+  DOKKU_APP_USER=${DOKKU_APP_USER:="herokuishuser"}
   local USER_VALUE
 
   if [[ -z "$IMAGE" ]]; then
     return 1
   fi
 
-  # due to how the build process works, all herokuish images have the Environment variable USER=herokuishuser
-  USER_VALUE="$("$DOCKER_BIN" image inspect --format '{{range .Config.Env}}{{if eq . "USER=herokuishuser" }}{{println .}}{{end}}{{end}}' "$IMAGE")"
+  # due to how the build process works, all herokuish images have the Environment variable USER=$DOKKU_APP_USER
+  USER_VALUE="$("$DOCKER_BIN" image inspect --format '{{range .Config.Env}}{{if eq . "USER='"$DOKKU_APP_USER"'"}}{{println .}}{{end}}{{end}}' "$IMAGE")"
   [[ "$USER_VALUE" == "" ]] && return 1
   return 0
 }
@@ -395,7 +401,7 @@ copy_from_image() {
 
   if verify_image "$IMAGE"; then
     if ! is_abs_path "$SRC_FILE"; then
-      if is_image_herokuish_based "$IMAGE"; then
+      if is_image_herokuish_based "$IMAGE" "$APP"; then
         WORKDIR="/app"
       else
         WORKDIR="$("$DOCKER_BIN" image inspect --format '{{.Config.WorkingDir}}' "$IMAGE")"
@@ -583,7 +589,7 @@ release_and_deploy() {
   verify_app_name "$APP"
 
   if verify_image "$IMAGE"; then
-    if is_image_herokuish_based "$IMAGE"; then
+    if is_image_herokuish_based "$IMAGE" "$APP"; then
       local IMAGE_SOURCE_TYPE="herokuish"
     else
       local IMAGE_SOURCE_TYPE="dockerfile"
diff --git a/plugins/config/docker-args-deploy b/plugins/config/docker-args-deploy
index f47712ce7..4334e5839 100755
--- a/plugins/config/docker-args-deploy
+++ b/plugins/config/docker-args-deploy
@@ -14,7 +14,7 @@ config_docker_args() {
   trigger="$0 config_docker_args"
   verify_app_name "$APP"
 
-  if ! is_image_herokuish_based "$IMAGE"; then
+  if ! is_image_herokuish_based "$IMAGE" "$APP"; then
     ENV_ARGS="$(config_export app "$APP" --format docker-args --merged)"
     echo -n "$STDIN $ENV_ARGS"
   else
diff --git a/plugins/enter/subcommands/default b/plugins/enter/subcommands/default
index 35e8b06bb..10b7a2402 100755
--- a/plugins/enter/subcommands/default
+++ b/plugins/enter/subcommands/default
@@ -58,7 +58,7 @@ enter_default_cmd() {
 
   local EXEC_CMD=""
   has_tty && local DOKKU_RUN_OPTS+=" -i -t"
-  is_image_herokuish_based "$IMAGE" && local EXEC_CMD="/exec"
+  is_image_herokuish_based "$IMAGE" "$APP" && local EXEC_CMD="/exec"
   # shellcheck disable=SC2086
   "$DOCKER_BIN" container exec $DOKKU_RUN_OPTS $ID $EXEC_CMD "${@:-$DOKKU_APP_SHELL}"
 }
diff --git a/plugins/network/network.go b/plugins/network/network.go
index eab00bb06..be9b98a44 100644
--- a/plugins/network/network.go
+++ b/plugins/network/network.go
@@ -37,7 +37,7 @@ func BuildConfig(appName string) {
 	}
 
 	image := common.GetAppImageName(appName, "", "")
-	isHerokuishContainer := common.IsImageHerokuishBased(image)
+	isHerokuishContainer := common.IsImageHerokuishBased(image, appName)
 	common.LogInfo1(fmt.Sprintf("Ensuring network configuration is in sync for %s", appName))
 	lines, err := common.FileToSlice(scaleFile)
 	if err != nil {
diff --git a/plugins/scheduler-docker-local/scheduler-deploy b/plugins/scheduler-docker-local/scheduler-deploy
index 6138f081f..8bd49aa83 100755
--- a/plugins/scheduler-docker-local/scheduler-deploy
+++ b/plugins/scheduler-docker-local/scheduler-deploy
@@ -25,7 +25,7 @@ scheduler-docker-local-scheduler-deploy() {
   verify_app_name "$APP"
   plugn trigger pre-deploy "$APP" "$IMAGE_TAG"
 
-  is_image_herokuish_based "$IMAGE" && DOKKU_HEROKUISH=true
+  is_image_herokuish_based "$IMAGE" "$APP" && DOKKU_HEROKUISH=true
   local IMAGE_SOURCE_TYPE="dockerfile"
   [[ "$DOKKU_HEROKUISH" == "true" ]] && IMAGE_SOURCE_TYPE="herokuish"
   local DOKKU_SCALE_FILE="$DOKKU_ROOT/$APP/DOKKU_SCALE"
diff --git a/plugins/scheduler-docker-local/scheduler-run b/plugins/scheduler-docker-local/scheduler-run
index aa6b27c84..fd0150aea 100755
--- a/plugins/scheduler-docker-local/scheduler-run
+++ b/plugins/scheduler-docker-local/scheduler-run
@@ -34,7 +34,7 @@ scheduler-docker-local-scheduler-run() {
 
   local DYNO_NUMBER="$RANDOM"
   local IMAGE_SOURCE_TYPE="dockerfile"
-  is_image_herokuish_based "$IMAGE" && IMAGE_SOURCE_TYPE="herokuish"
+  is_image_herokuish_based "$IMAGE" "$APP" && IMAGE_SOURCE_TYPE="herokuish"
   DOCKER_ARGS+=$(: | plugn trigger docker-args-process-run "$APP" "$IMAGE_TAG" "$IMAGE_SOURCE_TYPE")
   DOCKER_ARGS+=" -e DYNO=run.$DYNO_NUMBER --name $APP.run.$DYNO_NUMBER"
 
diff --git a/tests/unit/30_core_1.bats b/tests/unit/30_core_1.bats
index 3811b8a1c..dad84f1ab 100644
--- a/tests/unit/30_core_1.bats
+++ b/tests/unit/30_core_1.bats
@@ -186,3 +186,42 @@ EOF
   echo "status: $status"
   assert_output "3001/udp 3000/tcp 3003"
 }
+
+@test "(core) image type detection (herokuish default user)" {
+  export DOKKU_ROOT
+  deploy_app
+  source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
+  source "$PLUGIN_CORE_AVAILABLE_PATH/config/functions"
+
+  run is_image_herokuish_based "dokku/$TEST_APP" "$TEST_APP"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+}
+
+@test "(core) image type detection (herokuish custom user)" {
+  export DOKKU_ROOT
+  deploy_app
+  CID=$(< "$DOKKU_ROOT/$TEST_APP/CONTAINER.web.1")
+  docker commit --change "ENV USER postgres" "$CID" "dokku/${TEST_APP}:latest"
+  dokku config:set --no-restart "$TEST_APP" DOKKU_APP_USER=postgres
+  source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
+  source "$PLUGIN_CORE_AVAILABLE_PATH/config/functions"
+
+  run is_image_herokuish_based "dokku/$TEST_APP" "$TEST_APP"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+}
+
+@test "(core) image type detection (dockerfile)" {
+  export DOKKU_ROOT
+  deploy_app dockerfile
+  source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
+  source "$PLUGIN_CORE_AVAILABLE_PATH/config/functions"
+
+  run is_image_herokuish_based "dokku/$TEST_APP" "$TEST_APP"
+  echo "output: $output"
+  echo "status: $status"
+  assert_failure
+}
diff --git a/tests/unit/test_helper.bash b/tests/unit/test_helper.bash
index 7381ed9d1..71e002da1 100644
--- a/tests/unit/test_helper.bash
+++ b/tests/unit/test_helper.bash
@@ -2,6 +2,7 @@
 
 # constants
 DOKKU_ROOT=${DOKKU_ROOT:=~dokku}
+DOCKER_BIN=${DOCKER_BIN:="docker"}
 DOKKU_LIB_ROOT=${DOKKU_LIB_PATH:="/var/lib/dokku"}
 PLUGIN_PATH=${PLUGIN_PATH:="$DOKKU_LIB_ROOT/plugins"}
 PLUGIN_AVAILABLE_PATH=${PLUGIN_AVAILABLE_PATH:="$PLUGIN_PATH/available"}