diff --git a/plugins/ps/commands b/plugins/ps/commands
index e6e35c916..8855ba21f 100755
--- a/plugins/ps/commands
+++ b/plugins/ps/commands
@@ -7,7 +7,7 @@ release_and_deploy() {
   source "$(dirname $0)/../common/functions"
   local APP="$1"; local IMAGE="dokku/$APP"
 
-  if ls $DOKKU_ROOT/$APP/CONTAINER.* &> /dev/null; then
+  if verify_app_image "$APP"; then
     if is_image_buildstep_based "$IMAGE"; then
       IMAGE_SOURCE_TYPE="buildstep"
     else
diff --git a/plugins/ps/functions b/plugins/ps/functions
index 73b2d6de9..d77af8d1d 100755
--- a/plugins/ps/functions
+++ b/plugins/ps/functions
@@ -31,7 +31,7 @@ generate_scale_file() {
     fi
 
     dokku_log_info1_quiet "New DOKKU_SCALE file generated"
-    dokku_log_info1_quiet "$(< $DOKKU_SCALE_FILE)"
+    dokku_log_info2_quiet "$(< $DOKKU_SCALE_FILE)"
   fi
 }
 
@@ -42,6 +42,7 @@ set_scale() {
   for procscale in "${SCALE_SETTINGS[@]}"; do
     PROC_NAME=${procscale%%=*}
     PROC_COUNT=${procscale#*=}
+    is_number $PROC_COUNT || dokku_log_fail "ps:scale $PROC_COUNT is not a number"
     dokku_log_info1_quiet "Scaling $APP:$PROC_NAME to $PROC_COUNT"
     if (egrep -q ^${PROC_NAME}= $DOKKU_SCALE_FILE > /dev/null 2>&1);then
       sed --in-place "s:^${PROC_NAME}=.*:$PROC_NAME=$PROC_COUNT:g" $DOKKU_SCALE_FILE