diff --git a/src/sparsemap.c b/src/sparsemap.c
index a34ad6c..1636d63 100644
--- a/src/sparsemap.c
+++ b/src/sparsemap.c
@@ -1280,7 +1280,7 @@ sparsemap_merge(sparsemap_t *map, sparsemap_t *other)
       __sm_chunk_t src_chunk;
       __sm_chunk_map_init(&src_chunk, src + sizeof(sm_idx_t));
       size_t src_size = __sm_chunk_map_get_size(&src_chunk);
-      __sm_insert_data(map, src_start, src, src_size);
+      __sm_insert_data(map, dst_start, src, src_size);
       *(sm_idx_t *)dst = src_start;
 
       /* Update the chunk count and data_used. */