diff --git a/src/ccutil/unicity_table.h b/src/ccutil/unicity_table.h
index 8a894036db..4108995080 100644
--- a/src/ccutil/unicity_table.h
+++ b/src/ccutil/unicity_table.h
@@ -62,6 +62,13 @@ class UnicityTable {
     return table_.at(id);
   }
 
+  T &operator[](size_t id) {
+    return table_[id];
+  }
+  const T &operator[](size_t id) const {
+    return table_[id];
+  }
+
   /// Return the id of the T object.
   /// This method NEEDS a compare_callback to be passed to
   /// set_compare_callback.
diff --git a/src/classify/intproto.cpp b/src/classify/intproto.cpp
index b4a49c0056..854026bcc9 100644
--- a/src/classify/intproto.cpp
+++ b/src/classify/intproto.cpp
@@ -509,7 +509,7 @@ INT_TEMPLATES_STRUCT *Classify::CreateIntTemplates(CLASSES FloatProtos,
     FontSet fs;
     fs.reserve(fs_size);
     for (unsigned i = 0; i < fs_size; ++i) {
-      fs.push_back(FClass->font_set.at(i));
+      fs.push_back(FClass->font_set[i]);
     }
     IClass->font_set_id = this->fontset_table_.push_back(fs);
     AddIntClass(IntTemplates, ClassId, IClass);