diff --git a/include/flatbuffers/flatbuffers.h b/include/flatbuffers/flatbuffers.h
index b94846686..2f4e3cf15 100644
--- a/include/flatbuffers/flatbuffers.h
+++ b/include/flatbuffers/flatbuffers.h
@@ -587,7 +587,7 @@ class vector_downward {
     return static_cast<uoffset_t>(reserved_ - (cur_ - buf_));
   }
 
-  uoffset_t capacity() const {
+  size_t capacity() const {
     return reserved_;
   }