diff --git a/config/default.yml b/config/default.yml
index 9306b2f..f73da7b 100644
--- a/config/default.yml
+++ b/config/default.yml
@@ -110,6 +110,10 @@ function:
       4: array
     rb_funcallv_public:
       4: array
+    rb_gc_register_address:
+      1: in_ref
+    rb_gc_unregister_address:
+      1: in_ref
     rb_get_values_at:
       5: function
     rb_glob:
diff --git a/spec/ruby_header_parser/parser_spec.rb b/spec/ruby_header_parser/parser_spec.rb
index ccc2938..b829cdc 100644
--- a/spec/ruby_header_parser/parser_spec.rb
+++ b/spec/ruby_header_parser/parser_spec.rb
@@ -201,6 +201,36 @@
       its(:typeref)    { should eq typeref(type: "void") }
       its(:args)       { should eq args }
     end
+
+    context "rb_gc_register_address" do
+      subject { definitions.find { |d| d.name == "rb_gc_register_address" } }
+
+      let(:args) do
+        [
+          argument(type: "VALUE", name: "valptr", pointer: :in_ref),
+        ]
+      end
+
+      its(:name)       { should eq "rb_gc_register_address" }
+      its(:definition) { should eq "void rb_gc_register_address(VALUE *valptr)" }
+      its(:typeref)    { should eq typeref(type: "void") }
+      its(:args)       { should eq args }
+    end
+
+    context "rb_gc_unregister_address" do
+      subject { definitions.find { |d| d.name == "rb_gc_unregister_address" } }
+
+      let(:args) do
+        [
+          argument(type: "VALUE", name: "valptr", pointer: :in_ref),
+        ]
+      end
+
+      its(:name)       { should eq "rb_gc_unregister_address" }
+      its(:definition) { should eq "void rb_gc_unregister_address(VALUE *valptr)" }
+      its(:typeref)    { should eq typeref(type: "void") }
+      its(:args)       { should eq args }
+    end
   end
 
   describe "#extract_static_inline_function_definitions" do