diff --git a/lib/structured_params/params.rb b/lib/structured_params/params.rb
index 4c5c09e..1441a8f 100644
--- a/lib/structured_params/params.rb
+++ b/lib/structured_params/params.rb
@@ -73,10 +73,8 @@ def errors
     end
 
     # Convert structured objects to Hash and get attributes
-    #: (symbolize: true, compact: false) -> Hash[Symbol, untyped]
-    #: (symbolize: false, compact: false) -> Hash[String, untyped]
-    #: (symbolize: true, compact: true) -> Hash[Symbol, untyped]
-    #: (symbolize: false, compact: true) -> Hash[String, untyped]
+    #: (?symbolize: false, ?compact: bool) -> Hash[String, untyped]
+    #: (?symbolize: true, ?compact: bool) -> Hash[Symbol, untyped]
     def attributes(symbolize: false, compact: false)
       attrs = super()
 
@@ -154,8 +152,7 @@ def format_error_path(attr_name, index = nil)
     end
 
     # Serialize structured values
-    #: (bool, compact: false) -> untyped
-    #: (bool, compact: true) -> untyped
+    #: (bool, ?compact: bool) -> untyped
     def serialize_structured_value(value, compact: false)
       case value
       when Array
diff --git a/sig/structured_params/params.rbs b/sig/structured_params/params.rbs
index 10239fa..5039774 100644
--- a/sig/structured_params/params.rbs
+++ b/sig/structured_params/params.rbs
@@ -38,14 +38,10 @@ module StructuredParams
     def errors: () -> ::StructuredParams::Errors
 
     # Convert structured objects to Hash and get attributes
-    # : (symbolize: true, compact: false) -> Hash[Symbol, untyped]
-    # : (symbolize: false, compact: false) -> Hash[String, untyped]
-    # : (symbolize: true, compact: true) -> Hash[Symbol, untyped]
-    # : (symbolize: false, compact: true) -> Hash[String, untyped]
-    def attributes: (symbolize: true, compact: false) -> Hash[Symbol, untyped]
-                  | (symbolize: false, compact: false) -> Hash[String, untyped]
-                  | (symbolize: true, compact: true) -> Hash[Symbol, untyped]
-                  | (symbolize: false, compact: true) -> Hash[String, untyped]
+    # : (?symbolize: false, ?compact: bool) -> Hash[String, untyped]
+    # : (?symbolize: true, ?compact: bool) -> Hash[Symbol, untyped]
+    def attributes: (?symbolize: false, ?compact: bool) -> Hash[String, untyped]
+                  | (?symbolize: true, ?compact: bool) -> Hash[Symbol, untyped]
 
     private
 
@@ -74,10 +70,8 @@ module StructuredParams
     def format_error_path: (Symbol, Integer?) -> String
 
     # Serialize structured values
-    # : (bool, compact: false) -> untyped
-    # : (bool, compact: true) -> untyped
-    def serialize_structured_value: (bool, compact: false) -> untyped
-                                  | (bool, compact: true) -> untyped
+    # : (bool, ?compact: bool) -> untyped
+    def serialize_structured_value: (bool, ?compact: bool) -> untyped
 
     # Integrate structured parameter errors into parent errors
     # : (untyped, String) -> void