diff --git a/core/field_number.js b/core/field_number.js
index 396cac7f5..be5ac735d 100644
--- a/core/field_number.js
+++ b/core/field_number.js
@@ -274,6 +274,8 @@ Blockly.FieldNumber.prototype.doClassValidation_ = function(opt_newValue) {
   newValue = newValue.replace(/O/ig, '0');
   // Strip out thousands separators.
   newValue = newValue.replace(/,/g, '');
+  // Ignore case of 'Infinity'.
+  newValue = newValue.replace(/infinity/i, 'Infinity');
 
   // Clean up number.
   var n = Number(newValue || 0);