diff --git a/hilti/runtime/src/types/bytes.cc b/hilti/runtime/src/types/bytes.cc
index 75ea33a8df..10ad320566 100644
--- a/hilti/runtime/src/types/bytes.cc
+++ b/hilti/runtime/src/types/bytes.cc
@@ -215,6 +215,7 @@ Result<Bytes> Bytes::match(const RegExp& re, unsigned int group) const {
 }
 
 void Bytes::append(const stream::View& view) {
+    reserve(size() + view.size());
     for ( auto block = view.firstBlock(); block; block = view.nextBlock(block) )
         Base::append(reinterpret_cast<const char*>(block->start), block->size);
 }