diff --git a/lib/upload_creator.rb b/lib/upload_creator.rb
index e5c43dc0240..30b4ff99e6d 100644
--- a/lib/upload_creator.rb
+++ b/lib/upload_creator.rb
@@ -127,10 +127,14 @@ class UploadCreator
         if @image_info.type.to_s == 'svg'
           w, h = [0, 0]
 
+          # identify can behave differently depending on how it's compiled and
+          # what programs (e.g. inkscape) are installed on your system.
+          # 'MSVG:' forces ImageMagick to use internal routines and behave
+          # consistently whether it's running from our docker container or not
           begin
             w, h = Discourse::Utils
-              .execute_command("identify", "-ping", "-format", "%w %h", @file.path, timeout: Upload::MAX_IDENTIFY_SECONDS)
-              .split(' ')
+              .execute_command("identify", "-ping", "-format", "%w %h", "MSVG:#{@file.path}", timeout: Upload::MAX_IDENTIFY_SECONDS)
+              .split(' ').map(&:to_i)
           rescue
             # use default 0, 0
           end