1 files changed, 2 insertions, 2 deletions
diff --git a/activemodel/lib/active_model/validations/length.rb b/activemodel/lib/active_model/validations/length.rb
index 0eba241333..0bbd81a984 100644
--- a/activemodel/lib/active_model/validations/length.rb
+++ b/activemodel/lib/active_model/validations/length.rb
@@ -29,8 +29,8 @@ module ActiveModel
         keys.each do |key|
           value = options[key]
 
-          unless value.is_a?(Integer) && value >= 0
-            raise ArgumentError, ":#{key} must be a nonnegative Integer"
+          unless value.is_a?(Integer) && value >= 0 or value == Float::INFINITY
+            raise ArgumentError, ":#{key} must be a nonnegative Integer or Infinity"
           end
         end
       end