diff --git a/lib/steep/services/signature_help_provider.rb b/lib/steep/services/signature_help_provider.rb
index 515a4c985..b5a12dd38 100644
--- a/lib/steep/services/signature_help_provider.rb
+++ b/lib/steep/services/signature_help_provider.rb
@@ -14,12 +14,7 @@ def env
       def initialize(source:, subtyping:)
         @source = source
         @subtyping = subtyping
-
-        text =
-          if source.node
-            source.node.loc.expression.source
-          end
-        @buffer = RBS::Buffer.new(name: source.path, content: text || "")
+        @buffer = source.buffer
       end
 
       def run(line:, column:)
diff --git a/test/signature_help_provider_test.rb b/test/signature_help_provider_test.rb
index 22d0df66a..e1f4257e1 100644
--- a/test/signature_help_provider_test.rb
+++ b/test/signature_help_provider_test.rb
@@ -35,11 +35,12 @@ def self.foo: (String, Integer) -> Array[Symbol]
         end
       RBS
       source = Source.parse(<<~RUBY, path: Pathname("a.rb"), factory: checker.factory)
+        # Show signature help for a commented method call
         TestClass.foo("", 123)
       RUBY
 
       SignatureHelpProvider.new(source: source, subtyping: checker).tap do |provider|
-        items, index = provider.run(line: 1, column: 14)
+        items, index = provider.run(line: 2, column: 14)
 
         assert_equal 0, index
         assert_equal ["(::String, ::Integer) -> ::Array[::Symbol]", "() -> ::Array[::Symbol]"], items.map(&:method_type).map(&:to_s)