diff --git a/proto/ei-scanner b/proto/ei-scanner
index c451560..dd7e47e 100755
--- a/proto/ei-scanner
+++ b/proto/ei-scanner
@@ -440,11 +440,21 @@ class ProtocolParser(xml.sax.handler.ContentHandler):
         col = self._locator.getColumnNumber()  # type: ignore
         return line, col
 
-    def interface_by_name(self, name) -> Interface:
+    def interface_by_name(self, protocol_name: str) -> Interface:
+        """
+        Look up an interface by its protocol name (i.e. always "ei_foo", regardless of
+        what we're generating).
+        """
         try:
-            return [iface for iface in self.interfaces if iface.name == name].pop()
+            return [
+                iface
+                for iface in self.interfaces
+                if iface.protocol_name == protocol_name
+            ].pop()
         except IndexError:
-            raise XmlError.create(f"Unable to find interface {name}", self.location)
+            raise XmlError.create(
+                f"Unable to find interface {protocol_name}", self.location
+            )
 
     def startDocument(self):
         self._run_counter += 1
@@ -471,7 +481,7 @@ class ProtocolParser(xml.sax.handler.ContentHandler):
             # We only create the interface on the first run, in subsequent runs we
             # re-use them so we can cross reference correctly
             if self._run_counter > 1:
-                intf = self.interface_by_name(interface_name)
+                intf = self.interface_by_name(protocol_name)
             else:
                 intf = Interface.create(
                     name=interface_name,
@@ -631,9 +641,7 @@ class ProtocolParser(xml.sax.handler.ContentHandler):
             summary = attrs.get("summary", "")
             interface_name = attrs.get("interface", None)
             if interface_name is not None:
-                interface = self.interface_by_name(
-                    Interface.mangle_name(interface_name, self.component)
-                )
+                interface = self.interface_by_name(interface_name)
             else:
                 interface = None
             enum_name = attrs.get("enum", None)
@@ -641,9 +649,7 @@ class ProtocolParser(xml.sax.handler.ContentHandler):
             if enum_name is not None:
                 if "." in enum_name:
                     iname, enum_name = enum_name.split(".")
-                    intf = self.interface_by_name(
-                        Interface.mangle_name(iname, self.component)
-                    )
+                    intf = self.interface_by_name(iname)
                 else:
                     intf = self.current_interface