diff --git a/src/TooManyCells/Matrix/Load.hs b/src/TooManyCells/Matrix/Load.hs
--- a/src/TooManyCells/Matrix/Load.hs
+++ b/src/TooManyCells/Matrix/Load.hs
@@ -57,8 +57,8 @@
     -> CellFile
     -> MatrixFileFolder
     -> IO SingleCells
-loadCellrangerData _ _ (MatrixFile mf) = error (mf <> " must be a folder for matrix market format.")
-loadCellrangerData gf cf (MatrixFolder mf) = do
+loadCellrangerData _ _ (MatrixFolder mf) = error "Expected matrix.mtx, impossible error."
+loadCellrangerData gf cf (MatrixFile mf) = do
     let csvOptsTabs = CSV.defaultDecodeOptions { CSV.decDelimiter = fromIntegral (ord '\t') }
 
     m <- fmap (MatObsRow . HS.transposeSM . matToSpMat)  -- We want observations as rows
@@ -91,7 +91,7 @@
 loadHMatrixData :: Delimiter
                 -> MatrixFileFolder
                 -> IO SingleCells
-loadHMatrixData _ (MatrixFolder mf) = error $ mf <> " must be a csv for dense format."
+loadHMatrixData _ (MatrixFolder mf) = error "Expected matrix.mtx, impossible error."
 loadHMatrixData (Delimiter delim) (MatrixFile mf) = do
     let csvOpts = CSV.defaultDecodeOptions { CSV.decDelimiter = fromIntegral (ord delim) }
 
diff --git a/too-many-cells.cabal b/too-many-cells.cabal
--- a/too-many-cells.cabal
+++ b/too-many-cells.cabal
@@ -1,6 +1,6 @@
 cabal-version: >=1.10
 name: too-many-cells
-version: 0.1.2.0
+version: 0.1.2.1
 license: GPL-3
 license-file: LICENSE
 copyright: 2019 Gregory W. Schwartz