diff --git a/glue_ar/registries.py b/glue_ar/registries.py
index d7bdb3d..742a2bd 100644
--- a/glue_ar/registries.py
+++ b/glue_ar/registries.py
@@ -19,6 +19,7 @@ def add(self, extensions: Union[str, Tuple[str]], builder: Type):
     def __call__(self, extensions: Union[str, Tuple[str]]):
         def adder(builder: Type):
             self.add(extensions, builder)
+            return builder
         return adder
 
 
@@ -33,6 +34,7 @@ def add(self, name: str, compressor: Callable[[str], None]):
     def __call__(self, name: str):
         def adder(compressor: Callable[[str], None]):
             self.add(name, compressor)
+            return compressor
         return adder
 
 
diff --git a/glue_ar/tests/__init__.py b/glue_ar/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/glue_ar/tests/test_registries.py b/glue_ar/tests/test_registries.py
new file mode 100644
index 0000000..ed2070d
--- /dev/null
+++ b/glue_ar/tests/test_registries.py
@@ -0,0 +1,29 @@
+from ..registries import BuilderRegistry, CompressorRegistry
+
+
+def test_builder_registry():
+
+    builder_registry = BuilderRegistry()
+
+    @builder_registry("ext")
+    class ExtBuilder:
+        pass
+
+    @builder_registry(("ext1", "ext2"))
+    class ExtsBuilder:
+        pass
+
+    assert builder_registry.members == {"ext": ExtBuilder,
+                                        "ext1": ExtsBuilder,
+                                        "ext2": ExtsBuilder}
+
+
+def test_compressor_registry():
+
+    compressor_registry = CompressorRegistry()
+
+    @compressor_registry("dummy")
+    def dummy_compressor(_filepath: str):
+        pass
+
+    assert compressor_registry.members == {"dummy": dummy_compressor}