diff --git a/R/computeDiffInCounts.R b/R/computeDiffInCounts.R
index c8abbfa..10a3beb 100644
--- a/R/computeDiffInCounts.R
+++ b/R/computeDiffInCounts.R
@@ -4,20 +4,14 @@ computeDiffInCounts <- function(rows, max_noalle, nloci, data) {
   # % riveill� rows. rows pit�� olla vaakavektori.
 
   diffInCounts <- zeros(max_noalle, nloci)
-  for (i in seq_len(nrow(data))) {
+  for (i in rows) { # yep, just one iteration
     row <- data[i, ]
     notEmpty <- as.matrix(matlab2r::find(row >= 0))
 
     if (length(notEmpty) > 0) {
-      diffInCounts[row(notEmpty) + (notEmpty - 1) * max_noalle] <-
-        diffInCounts[row(notEmpty) + (notEmpty - 1) * max_noalle] + 1
+      element <- row[notEmpty] + (notEmpty - 1) * max_noalle
+      diffInCounts[element] <- diffInCounts[element] + 1
     }
   }
-  diffInCounts <- matrix(
-    data = diffInCounts[!is.na(diffInCounts)],
-    nrow = max_noalle,
-    ncol = nloci,
-    byrow = TRUE
-  )
   return(diffInCounts)
 }