diff --git a/byte-count-reader.cabal b/byte-count-reader.cabal
--- a/byte-count-reader.cabal
+++ b/byte-count-reader.cabal
@@ -1,6 +1,6 @@
 cabal-version: 2.2
 name: byte-count-reader
-version: 0.10.1.5
+version: 0.10.1.6
 license: GPL-3.0-only
 license-file: LICENSE
 copyright: 2021 Daniel Rolls
diff --git a/test/Spec.hs b/test/Spec.hs
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -7,24 +7,40 @@
 main = hspec $ 
      do it "Unparsable strings should return Nothing" $
              sizeInBytes "unparseable" `shouldBe` Nothing
+        it "Unknown units should return nothing" $
+             sizeInBytes "5 Z" `shouldBe` Nothing
+        it "Unknown units for base 2 function should return nothing" $
+             sizeInBytesAssumingBase2 "5 Z" `shouldBe` Nothing
         testHappyPathScenarios sizeInBytes
-          [ ("1 kb", 1000)
+          [
+            ("1b", 1)
+          , ("2 b", 2)
+          , ("1 kb", 1000)
           , ("0.5 kib", 512)
           , ("1 kib", 1024)
           , ("2 kb", 2000)
           , ("3 kb", 3000)
+          , ("2 mB", 2000000)
           , (".5 MiB", 524288)
+          , ("2 gB", 2000000000)
           , ("4 GiB", 4294967296)
+          , ("4      Tb", 4000000000000)
           , ("1      tIb", 1099511627776)
           ]
         testHappyPathScenarios sizeInBytesAssumingBase2
-          [ ("1 kb", 1024)
+          [ 
+            ("0 b", 0)
+          , ("5 b", 5)
+          , ("1 kb", 1024)
           , ("0.5 kib", 512)
           , ("1 kib", 1024)
           , ("2 kb", 2048)
           , ("3 kb", 3072)
+          , ("1 MB", 1048576)
           , (".5 MiB", 524288)
+          , ("4 gB", 4294967296)
           , ("4 GiB", 4294967296)
+          , ("2 TB", 2199023255552)
           , ("2 TiB", 2199023255552)
           ]
         where testHappyPathScenarios functionUnderTest = foldl (>>) (return ()) . map (parseTest functionUnderTest)