diff --git a/Steepfile b/Steepfile
index d929e524..3c4f357c 100644
--- a/Steepfile
+++ b/Steepfile
@@ -9,6 +9,7 @@ target :lib do
   check "lib/lrama/grammar"
   check "lib/lrama/lexer"
   check "lib/lrama/report"
+  check "lib/lrama/state"
   check "lib/lrama/bitmap.rb"
   check "lib/lrama/digraph.rb"
   check "lib/lrama/grammar.rb"
diff --git a/lib/lrama/state/reduce.rb b/lib/lrama/state/reduce.rb
index 45d509f7..a2b7c26c 100644
--- a/lib/lrama/state/reduce.rb
+++ b/lib/lrama/state/reduce.rb
@@ -27,6 +27,7 @@ def add_not_selected_symbol(sym)
 
       def selected_look_ahead
         if @look_ahead
+          # @type ivar @look_ahead: Array<Grammar::Symbol>
           @look_ahead - @not_selected_symbols
         else
           []
diff --git a/lib/lrama/state/resolved_conflict.rb b/lib/lrama/state/resolved_conflict.rb
index 6b67f36b..3bb3d144 100644
--- a/lib/lrama/state/resolved_conflict.rb
+++ b/lib/lrama/state/resolved_conflict.rb
@@ -8,7 +8,7 @@ class State
     class ResolvedConflict < Struct.new(:symbol, :reduce, :which, :same_prec, keyword_init: true)
       def report_message
         s = symbol.display_name
-        r = reduce.rule.precedence_sym.display_name
+        r = reduce.rule.precedence_sym&.display_name
         case
         when which == :shift && same_prec
           msg = "resolved as #{which} (%right #{s})"
diff --git a/sig/lrama/state/reduce.rbs b/sig/lrama/state/reduce.rbs
new file mode 100644
index 00000000..be98d5bc
--- /dev/null
+++ b/sig/lrama/state/reduce.rbs
@@ -0,0 +1,20 @@
+module Lrama
+  class State
+    class Reduce
+      @item: States::Item
+      @look_ahead: Array[Grammar::Symbol]?
+      @not_selected_symbols: Array[Grammar::Symbol]
+
+      attr_reader item: States::Item
+      attr_reader look_ahead: Array[Grammar::Symbol]?
+      attr_reader not_selected_symbols: Array[Grammar::Symbol]
+      attr_accessor default_reduction: bool
+
+      def initialize: (States::Item item) -> void
+      def rule: -> Grammar::Rule
+      def look_ahead=: (Array[Grammar::Symbol] look_ahead) -> Array[Grammar::Symbol]
+      def add_not_selected_symbol: (Grammar::Symbol sym) -> Array[Grammar::Symbol]
+      def selected_look_ahead: () -> (::Array[Grammar::Symbol?])
+    end
+  end
+end
diff --git a/sig/lrama/state/reduce_reduce_conflict.rbs b/sig/lrama/state/reduce_reduce_conflict.rbs
new file mode 100644
index 00000000..23ced680
--- /dev/null
+++ b/sig/lrama/state/reduce_reduce_conflict.rbs
@@ -0,0 +1,13 @@
+module Lrama
+  class State
+    class ReduceReduceConflict
+      attr_accessor symbols: Array[Grammar::Symbol?]
+      attr_accessor reduce1: State::Reduce
+      attr_accessor reduce2: State::Reduce
+
+      def initialize: (?symbols: Array[Grammar::Symbol?], ?reduce1: State::Reduce, ?reduce2: State::Reduce) -> void
+
+      def type: () -> :reduce_reduce
+    end
+  end
+end
diff --git a/sig/lrama/state/resolved_conflict.rbs b/sig/lrama/state/resolved_conflict.rbs
new file mode 100644
index 00000000..76be9469
--- /dev/null
+++ b/sig/lrama/state/resolved_conflict.rbs
@@ -0,0 +1,14 @@
+module Lrama
+  class State
+    class ResolvedConflict
+      attr_accessor symbol: Grammar::Symbol
+      attr_accessor reduce: State::Reduce
+      attr_accessor which: (:reduce | :shift)
+      attr_accessor same_prec: bool
+
+      def initialize: (?symbol: Grammar::Symbol, ?reduce: State::Reduce, ?which: (:reduce | :shift), ?same_prec: bool) -> void
+
+      def report_message: () -> (::String | bot)
+    end
+  end
+end
diff --git a/sig/lrama/state/shift.rbs b/sig/lrama/state/shift.rbs
new file mode 100644
index 00000000..f1dd0e89
--- /dev/null
+++ b/sig/lrama/state/shift.rbs
@@ -0,0 +1,14 @@
+module Lrama
+  class State
+    class Shift
+      @next_sym: Grammar::Symbol
+      @next_items: Array[States::Item]
+
+      attr_reader next_sym: Grammar::Symbol
+      attr_reader next_items: Array[States::Item]
+      attr_accessor not_selected: bool
+
+      def initialize: (Grammar::Symbol next_sym, Array[States::Item] next_items) -> void
+    end
+  end
+end
diff --git a/sig/lrama/state/shift_reduce_conflict.rbs b/sig/lrama/state/shift_reduce_conflict.rbs
new file mode 100644
index 00000000..af878342
--- /dev/null
+++ b/sig/lrama/state/shift_reduce_conflict.rbs
@@ -0,0 +1,13 @@
+module Lrama
+  class State
+    class ShiftReduceConflict
+      attr_accessor symbols: Array[Grammar::Symbol]
+      attr_accessor shift: State::Shift
+      attr_accessor reduce: State::Reduce
+
+      def initialize: (?symbols: Array[Grammar::Symbol], ?shift: State::Shift, ?reduce: State::Reduce) -> void
+
+      def type: () -> :shift_reduce
+    end
+  end
+end
diff --git a/sig/lrama/states/item.rbs b/sig/lrama/states/item.rbs
new file mode 100644
index 00000000..45a58ca2
--- /dev/null
+++ b/sig/lrama/states/item.rbs
@@ -0,0 +1,44 @@
+module Lrama
+  class States
+    class Item
+      extend Forwardable
+
+      attr_accessor rule: untyped
+      attr_accessor position: Integer
+
+      # Optimization for States#setup_state
+      def hash: () -> untyped
+
+      def rule_id: () -> untyped
+
+      def empty_rule?: () -> untyped
+
+      def number_of_rest_symbols: () -> untyped
+
+      def next_sym: () -> untyped
+
+      def next_next_sym: () -> untyped
+
+      def previous_sym: () -> untyped
+
+      def end_of_rule?: () -> untyped
+
+      def beginning_of_rule?: () -> untyped
+
+      def start_item?: () -> untyped
+
+      def new_by_next_position: () -> untyped
+
+      def symbols_before_dot: () -> untyped
+
+      def symbols_after_dot: () -> untyped
+
+      def to_s: () -> ::String
+
+      def display_name: () -> ::String
+
+      # Right after position
+      def display_rest: () -> ::String
+    end
+  end
+end