diff --git a/R/collapse_rows.R b/R/collapse_rows.R
index ee05cc8..86956aa 100644
--- a/R/collapse_rows.R
+++ b/R/collapse_rows.R
@@ -109,7 +109,7 @@
   mapping_matrix <- list()
   for (i in columns) {
     mapping_matrix[[paste0("x", i)]] <- unlist(lapply(
-      rle(kable_dt[, i])$length, column_block))
+      rle(kable_dt[, i])$lengths, column_block))
   }
   mapping_matrix <- data.frame(mapping_matrix)
   return(mapping_matrix)