diff --git a/proto/scanner.py b/proto/scanner.py
index 5244c3a..d9ab8b8 100755
--- a/proto/scanner.py
+++ b/proto/scanner.py
@@ -70,6 +70,7 @@ class Argument:
     name: str = attr.ib()
     signature: str = attr.ib(converter=proto_to_type)
     summary: str = attr.ib()
+    enum: Optional["Enum"] = attr.ib()
 
     @property
     def as_arg(self) -> str:
@@ -105,9 +106,10 @@ class Argument:
         assert value in types, f"Failed to parse signature {value}"
 
     @classmethod
-    def create(cls, name: str, signature: str, summary: str = "") -> "Argument":
-        # FIXME: enum value checks
-        return cls(name, signature, summary)
+    def create(
+        cls, name: str, signature: str, summary: str = "", enum: Optional["Enum"] = None
+    ) -> "Argument":
+        return cls(name, signature, summary, enum)
 
 
 @attr.s
@@ -313,7 +315,12 @@ class Protocol(xml.sax.handler.ContentHandler):
             name = attrs["name"]
             sig = attrs["type"]
             summary = attrs.get("summary", "")
-            arg = Argument.create(name=name, signature=sig, summary=summary)
+            enum = attrs.get("enum", None)
+            if enum is not None:
+                assert enum in [
+                    e.name for e in self.current_interface.enums
+                ], f"Failed to find enum '{self.current_interface.name}.{enum}'"
+            arg = Argument.create(name=name, signature=sig, summary=summary, enum=enum)
             self.current_message.add_argument(arg)
         elif element == "entry":
             assert self.current_interface is not None