diff --git a/src/structs/dmat.rs b/src/structs/dmat.rs
index 2982c184..4d00f954 100644
--- a/src/structs/dmat.rs
+++ b/src/structs/dmat.rs
@@ -139,7 +139,7 @@ impl<N> DMat<N> {
         DMat {
             nrows: nrows,
             ncols: ncols,
-            mij:   Vec::from_fn(nrows * ncols, |i| f(i % nrows, i / nrows))
+            mij:   Vec::from_fn(nrows * ncols, |i| { let m = i / nrows; f(i - m * nrows, m) })
         }
     }