diff --git a/internal/core/src/mmap/Column.h b/internal/core/src/mmap/Column.h
index bba308ec4b..fd965c35a7 100644
--- a/internal/core/src/mmap/Column.h
+++ b/internal/core/src/mmap/Column.h
@@ -319,10 +319,10 @@ class VariableColumn : public ColumnBase {
             indices_ = std::move(indices);
         }
 
+        num_rows_ = indices_.size();
+
         // for variable length column in memory mode only
         if (data_ == nullptr) {
-            num_rows_ = indices_.size();
-
             size_t total_size = size_;
             size_ = 0;
             Expand(total_size);