diff --git a/src/registry/mod.rs b/src/registry/mod.rs
index 4b2b9cce..a8d1a7ff 100644
--- a/src/registry/mod.rs
+++ b/src/registry/mod.rs
@@ -372,30 +372,11 @@ impl Registry {
         T::qualified_type_name()
     }
 
-    pub fn create_dummy_type<T: crate::Type>(&mut self) -> MetaType {
-        let mut dummy_registry = Registry::default();
-        T::create_type_info(&mut dummy_registry);
-        if let Some(ty) = dummy_registry.types.remove(&*T::type_name()) {
-            // Do not overwrite existing types.
-            for (name, ty) in dummy_registry.types {
-                if !self.types.contains_key(&name) {
-                    self.types.insert(name, ty);
-                }
-            }
-
-            // Do not overwrite existing implements.
-            for (name, interfaces) in dummy_registry.implements {
-                if let Some(current_interfaces) = self.implements.get_mut(&name) {
-                    current_interfaces.extend(interfaces);
-                } else {
-                    self.implements.insert(name, interfaces);
-                }
-            }
-
-            ty
-        } else {
-            unreachable!()
-        }
+    pub fn create_dummy_type<T: Type>(&mut self) -> MetaType {
+        T::create_type_info(self);
+        self.types
+            .remove(&*T::type_name())
+            .expect("You definitely encountered a bug!")
     }
 
     pub fn add_directive(&mut self, directive: MetaDirective) {
diff --git a/src/registry/stringify_exec_doc.rs b/src/registry/stringify_exec_doc.rs
index 7e7278d0..b926156e 100644
--- a/src/registry/stringify_exec_doc.rs
+++ b/src/registry/stringify_exec_doc.rs
@@ -43,7 +43,7 @@ impl Registry {
                         }
                         write!(
                             output,
-                            "{}: {}",
+                            "${}: {}",
                             variable_definition.node.name.node,
                             variable_definition.node.var_type.node
                         )?;
@@ -259,7 +259,7 @@ mod tests {
                     &doc
                 )
                 .unwrap(),
-            r#"query Abc { value(input: 10) }"#
+            r#"query Abc($a: Int) { value(input: 10) }"#
         );
     }