diff --git a/app/helpers/previews_helper.rb b/app/helpers/previews_helper.rb
index dc7a0097..bab83e55 100644
--- a/app/helpers/previews_helper.rb
+++ b/app/helpers/previews_helper.rb
@@ -9,7 +9,7 @@ def download_text(dataset, datafile)
 
   def numeric?(value)
     value.to_s.match?(/\A
-                      \-? # may be negative
+                      -? # may be negative
                       (
                         \d+(\.\d+)? # digits, potential followed by decimal
                         |