diff --git a/lib/spoom.rb b/lib/spoom.rb
index 81f7cb82..30d312a2 100644
--- a/lib/spoom.rb
+++ b/lib/spoom.rb
@@ -22,3 +22,5 @@ class Error < StandardError; end
 require "spoom/sorbet"
 require "spoom/cli"
 require "spoom/version"
+
+require "spoom/ext/prism_types"
diff --git a/lib/spoom/ext/prism_types.rb b/lib/spoom/ext/prism_types.rb
new file mode 100644
index 00000000..2187aa12
--- /dev/null
+++ b/lib/spoom/ext/prism_types.rb
@@ -0,0 +1,14 @@
+# typed: strict
+# frozen_string_literal: true
+
+module Spoom
+  module PrismTypes
+    # Ideally this would just be in a shim in `sorbet/rbi/shims/prism.rbi`, but that causes
+    # `bundle exec tapioca gem spoom` to fail. It Spoom's translator to rewrite the RBS signature comments into Sigs,
+    # which try to access the `Prism::AnyScopeNode` constant.
+    # Because shims aren't executed, no such constant exists at runtime, and the Sig raises a NameError.
+    #
+    # So instead, we define it here, where the translator can reify it into a real Sorbet `T.type_alias` at runtime.
+    #: type anyScopeNode = ::Prism::ClassNode | ::Prism::ModuleNode | ::Prism::SingletonClassNode
+  end
+end
diff --git a/lib/spoom/sorbet/metrics/code_metrics_visitor.rb b/lib/spoom/sorbet/metrics/code_metrics_visitor.rb
index b6ed0f66..4066954d 100644
--- a/lib/spoom/sorbet/metrics/code_metrics_visitor.rb
+++ b/lib/spoom/sorbet/metrics/code_metrics_visitor.rb
@@ -147,7 +147,7 @@ def visit_call_node(node)
 
         private
 
-        #: (Prism::ClassNode | Prism::ModuleNode | Prism::SingletonClassNode) { -> void } -> void
+        #: (PrismTypes::anyScopeNode) { -> void } -> void
         def visit_scope(node, &block)
           key = node_key(node)
           @counters.increment(key)
@@ -216,7 +216,7 @@ def collect_last_srb_sigs
           sigs
         end
 
-        #: (Prism::ClassNode | Prism::ModuleNode | Prism::SingletonClassNode) -> String
+        #: (PrismTypes::anyScopeNode) -> String
         def node_key(node)
           case node
           when Prism::ClassNode
diff --git a/lib/spoom/sorbet/translate/rbs_comments_to_sorbet_sigs/base_translator.rb b/lib/spoom/sorbet/translate/rbs_comments_to_sorbet_sigs/base_translator.rb
index 2528ffe5..74979c7d 100644
--- a/lib/spoom/sorbet/translate/rbs_comments_to_sorbet_sigs/base_translator.rb
+++ b/lib/spoom/sorbet/translate/rbs_comments_to_sorbet_sigs/base_translator.rb
@@ -199,7 +199,7 @@ def apply_overloads_strategy(signatures, method_name:, location:)
             end
           end
 
-          #: (Prism::ClassNode | Prism::ModuleNode | Prism::SingletonClassNode) -> void
+          #: (PrismTypes::anyScopeNode) -> void
           def apply_class_annotations(node)
             comments = node_rbs_comments(node)
             return if comments.empty?
@@ -324,7 +324,7 @@ def apply_member_annotations(annotations, sig)
             end
           end
 
-          #: (Prism::ClassNode | Prism::ModuleNode | Prism::SingletonClassNode, Regexp) -> bool
+          #: (PrismTypes::anyScopeNode, Regexp) -> bool
           def already_extends?(node, constant_regex)
             node.child_nodes.any? do |c|
               next false unless c.is_a?(Prism::CallNode)
diff --git a/lib/spoom/sorbet/translate/sorbet_sigs_to_rbs_comments.rb b/lib/spoom/sorbet/translate/sorbet_sigs_to_rbs_comments.rb
index 619454e2..c6cc2c70 100644
--- a/lib/spoom/sorbet/translate/sorbet_sigs_to_rbs_comments.rb
+++ b/lib/spoom/sorbet/translate/sorbet_sigs_to_rbs_comments.rb
@@ -134,7 +134,7 @@ def visit_constant_write_node(node)
 
         private
 
-        #: (Prism::ClassNode | Prism::ModuleNode | Prism::SingletonClassNode) { -> void } -> void
+        #: (PrismTypes::anyScopeNode) { -> void } -> void
         def visit_scope(node, &block)
           old_class_annotations = @class_annotations
           @class_annotations = []
@@ -229,7 +229,7 @@ def visit_extend(node)
           end
         end
 
-        #: (Prism::ClassNode | Prism::ModuleNode | Prism::SingletonClassNode, Prism::CallNode) -> void
+        #: (PrismTypes::anyScopeNode, Prism::CallNode) -> void
         def apply_class_annotation(parent, node)
           unless node.message == "abstract!" || node.message == "interface!" || node.message == "sealed!" ||
               node.message == "final!" || node.message == "requires_ancestor"
diff --git a/rbi/spoom.rbi b/rbi/spoom.rbi
index a66ee297..308e511e 100644
--- a/rbi/spoom.rbi
+++ b/rbi/spoom.rbi
@@ -2572,6 +2572,8 @@ class Spoom::Printer
   def printt; end
 end
 
+module Spoom::PrismTypes; end
+Spoom::PrismTypes::AnyScopeNode = T.type_alias { T.any(::Prism::ClassNode, ::Prism::ModuleNode, ::Prism::SingletonClassNode) }
 module Spoom::RBS; end
 class Spoom::RBS::Annotation < ::Spoom::RBS::Comment; end