diff --git a/src/merge_types.js b/src/merge_types.js
index f6daee8..5769138 100644
--- a/src/merge_types.js
+++ b/src/merge_types.js
@@ -97,6 +97,12 @@ const _makeMergedFieldDefinitions = (merged, candidate) => _addCommentsToAST(can
     // retain directives of both fields.
     if (original) {
       original.directives = original.directives.concat(field.directives);
+      original.directives = original.directives.reduce((current, next) => {
+        if (current.findIndex(n => n.name.value === next.name.value) === -1) {
+          current.push(next);
+        }
+        return current;
+      }, []);
     }
     return fields;
   }, merged.fields);
diff --git a/test/graphql/other/query_type/stack_directives.js b/test/graphql/other/query_type/stack_directives.js
index af304eb..8852a9b 100644
--- a/test/graphql/other/query_type/stack_directives.js
+++ b/test/graphql/other/query_type/stack_directives.js
@@ -5,9 +5,12 @@ export default `
     age: Int
   }
   type Query {
-    client: Client @foo
+    client: Client @foo @foo
   }
   type Query {
     client: Client @bar
   }
+  type Query {
+    client: Client @foo @bar
+  }
 `;