diff --git a/hierarchical-spectral-clustering.cabal b/hierarchical-spectral-clustering.cabal
--- a/hierarchical-spectral-clustering.cabal
+++ b/hierarchical-spectral-clustering.cabal
@@ -1,6 +1,6 @@
 cabal-version: >=1.10
 name: hierarchical-spectral-clustering
-version: 0.4.1.0
+version: 0.4.1.1
 license: GPL-3
 license-file: LICENSE
 copyright: 2019 Gregory W. Schwartz
diff --git a/src/Math/Clustering/Hierarchical/Spectral/Utility.hs b/src/Math/Clustering/Hierarchical/Spectral/Utility.hs
--- a/src/Math/Clustering/Hierarchical/Spectral/Utility.hs
+++ b/src/Math/Clustering/Hierarchical/Spectral/Utility.hs
@@ -22,7 +22,7 @@
 subsetVector xs =
     V.fromList
         . F.foldr' (\ !i !acc
-                    -> ( fromMaybe (error "Out of bounds in subsetVector.")
+                    -> ( fromMaybe (error "Out of bounds in subsetVector (do the number of observations and features match the size of the matrix? Is the input format correct?).")
                       $ xs V.!? i
                       ) : acc
                     ) []