diff --git a/src/SymptomsCausedByVaccines/HtmlUtils.py b/src/SymptomsCausedByVaccines/HtmlUtils.py
index d3d79073769..e2d3f34ec2f 100644
--- a/src/SymptomsCausedByVaccines/HtmlUtils.py
+++ b/src/SymptomsCausedByVaccines/HtmlUtils.py
@@ -25,4 +25,4 @@ def _getOptions(values, filenameByValue):
 def _getOption(filename, displayValue):
     return '<option value="{value}">{displayValue}</option>'.format(
         value = filename,
-        displayValue = html.escape(displayValue))
+        displayValue = html.escape(str(displayValue)))