diff --git a/spec/unit/dry/cli/registry_spec.rb b/spec/unit/dry/cli/registry_spec.rb
index d6511f3..2c28d76 100644
--- a/spec/unit/dry/cli/registry_spec.rb
+++ b/spec/unit/dry/cli/registry_spec.rb
@@ -28,7 +28,9 @@
 
     context "when class is given" do
       it "raises error when #initialize arity is not equal to 0" do
-        callback = Struct
+        callback = Class.new do
+          def initialize(foo); end
+        end
 
         expect do
           Bar::CLI::Commands.before("alpha", callback)
@@ -64,7 +66,9 @@
 
     context "when class is given" do
       it "raises error when #initialize arity is not equal to 0" do
-        callback = Struct
+        callback = Class.new do
+          def initialize(foo); end
+        end
 
         expect do
           Bar::CLI::Commands.after("alpha", callback)