diff --git a/tailbone/templates/batch/inventory/desktop_form.mako b/tailbone/templates/batch/inventory/desktop_form.mako
index 1b1ef0f2..720084f6 100644
--- a/tailbone/templates/batch/inventory/desktop_form.mako
+++ b/tailbone/templates/batch/inventory/desktop_form.mako
@@ -10,11 +10,13 @@
 
     function assert_quantity() {
         % if allow_cases:
-        if ($('#cases').val() && parseFloat($('#cases').val())) {
+        var cases = parseFloat($('#cases').val());
+        if (!isNaN(cases)) {
             return true;
         }
         % endif
-        if ($('#units').val() && parseFloat($('#units').val())) {
+        var units = parseFloat($('#units').val());
+        if (!isNaN(units)) {
             return true;
         }
         alert("Please provide case and/or unit quantity");