diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,9 @@
 # Revision history for matrix-as-xyz
 
+## 0.1.1.1  -- 2018-06-09
+
+* 大文字が使用できなかった不具合の修正
+
 ## 0.1.1.0  -- 2018-06-05
 
 * CabalからStackに変更
diff --git a/matrix-as-xyz.cabal b/matrix-as-xyz.cabal
--- a/matrix-as-xyz.cabal
+++ b/matrix-as-xyz.cabal
@@ -2,10 +2,10 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 19899810c3d6696ddbcceefa6fcb228661c87238cefcfc1bcdde512fba3dd8ba
+-- hash: 6a225e76b978422309693298bada20249ab7d6023ddf7a05d2bdb4df6072a42b
 
 name:           matrix-as-xyz
-version:        0.1.1.0
+version:        0.1.1.1
 synopsis:       Read and Display representation of matrix like "x,y,z"
 description:    Please see the README on GitHub at <https://github.com/narumij/matrix-as-xyz#readme>
 category:       Chemistry
diff --git a/src/Data/Matrix/AsXYZ/Parse.hs b/src/Data/Matrix/AsXYZ/Parse.hs
--- a/src/Data/Matrix/AsXYZ/Parse.hs
+++ b/src/Data/Matrix/AsXYZ/Parse.hs
@@ -17,6 +17,7 @@
   ) where
 
 import Control.Monad
+import Data.Char
 import Data.Maybe
 import Data.List
 import Text.ParserCombinators.Parsec
@@ -95,13 +96,16 @@
   fmap f (Z a) = Z (f a)
   fmap f (W a) = W (f a)
 
-v (Just 'x') = X
-v (Just 'a') = X
-v (Just 'y') = Y
-v (Just 'b') = Y
-v (Just 'z') = Z
-v (Just 'c') = Z
-v Nothing = W
+v c = f $ toLower <$> c
+  where
+    f (Just 'x') = X
+    f (Just 'a') = X
+    f (Just 'y') = Y
+    f (Just 'b') = Y
+    f (Just 'z') = Z
+    f (Just 'c') = Z
+    f (Just 'Z') = Z
+    f Nothing = W
 
 sign :: CharParser () Char
 sign = oneOf "-+"
diff --git a/test/AsXYZSpec.hs b/test/AsXYZSpec.hs
--- a/test/AsXYZSpec.hs
+++ b/test/AsXYZSpec.hs
@@ -18,6 +18,14 @@
      it "read x,y,z" $ do
        fromXYZ "x,y,z" `shouldBe` (identity 4)
 
+     it "read X,Y,Z" $ do
+       fromXYZ "X,Y,Z" `shouldBe` (identity 4)
+
+     it "read a,b,c" $ do
+       fromABC "a,b,c" `shouldBe` (identity 4)
+
+     it "read A,B,C" $ do
+       fromABC "A,B,C" `shouldBe` (identity 4)
 
    describe "Data.Matrix.AsXYZ.prettyXYZ" $ do