diff --git a/flaschengeist/cli/InterfaceGenerator.py b/flaschengeist/cli/InterfaceGenerator.py
index 177a1a9..3bcb545 100644
--- a/flaschengeist/cli/InterfaceGenerator.py
+++ b/flaschengeist/cli/InterfaceGenerator.py
@@ -1,3 +1,4 @@
+import io
 import sys
 import inspect
 import logging
@@ -93,15 +94,32 @@ class InterfaceGenerator:
         self.basename = models.__name__
         self.walker(("models", models))
 
+    def _write_types(self):
+        TYPE = "type {name} = {alias};\n"
+        INTERFACE = "interface {name} {{\n{properties}}}\n"
+        PROPERTY = "\t{name}{modifier}: {type};\n"
+
+        buffer = io.StringIO()
+        for cls, props in self.classes.items():
+            if isinstance(props, str):
+                buffer.write(TYPE.format(name=cls, alias=props))
+            else:
+                buffer.write(
+                    INTERFACE.format(
+                        name=cls,
+                        properties="".join(
+                            [PROPERTY.format(name=name, modifier=props[name][0], type=props[name][1]) for name in props]
+                        ),
+                    )
+                )
+        return buffer
+
     def write(self):
         with (open(self.filename, "w") if self.filename else sys.stdout) as file:
-            file.write("declare namespace {} {{\n".format(self.namespace))
-            for cls, params in self.classes.items():
-                if isinstance(params, str):
-                    file.write("\ttype {} = {};\n".format(cls, params))
-                else:
-                    file.write("\tinterface {} {{\n".format(cls))
-                    for name in params:
-                        file.write("\t\t{}{}: {};\n".format(name, *params[name]))
-                    file.write("\t}\n")
-            file.write("}\n")
+            if self.namespace:
+                file.write(f"declare namespace {self.namespace} {{\n")
+                for line in self._write_types().getvalue().split("\n"):
+                    file.write(f"\t{line}\n")
+                file.write("}\n")
+            else:
+                file.write(self._write_types().getvalue())