diff --git a/lib/unleash/constraint.rb b/lib/unleash/constraint.rb
index 104c7ef..53bc4ad 100644
--- a/lib/unleash/constraint.rb
+++ b/lib/unleash/constraint.rb
@@ -107,7 +107,7 @@ def matches_constraint?(context)
       context_value = context.get_by_name(self.context_name)
 
       v.map!(&:upcase) if self.case_insensitive
-      context_value = context_value.upcase if self.case_insensitive
+      context_value = context_value.upcase if self.case_insensitive # && context_value.is_a?(String)
 
       OPERATORS[self.operator].call(context_value, v)
     end