diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 0.8.12
+
+* Proper handling of `String "+123"` [#64](https://github.com/snoyberg/yaml/issues/64)
+
 ## 0.8.11
 
 * Function to print prettier parse exceptions [#59](https://github.com/snoyberg/yaml/pull/59)
diff --git a/Data/Yaml.hs b/Data/Yaml.hs
--- a/Data/Yaml.hs
+++ b/Data/Yaml.hs
@@ -158,6 +158,7 @@
                 || c == 'E'
                 || c == '.'
                 || c == '-'
+                || c == '+'
 
 decode :: FromJSON a
        => ByteString
diff --git a/test/Data/Yaml/IncludeSpec.hs b/test/Data/Yaml/IncludeSpec.hs
--- a/test/Data/Yaml/IncludeSpec.hs
+++ b/test/Data/Yaml/IncludeSpec.hs
@@ -2,7 +2,7 @@
 module Data.Yaml.IncludeSpec (main, spec) where
 
 import           Test.Hspec
-import           Test.Hspec.Expectations.Contrib
+import           Data.Either.Compat
 import           Data.Aeson
 import           Data.Aeson.QQ
 import           Data.Yaml (ParseException)
diff --git a/test/Data/YamlSpec.hs b/test/Data/YamlSpec.hs
--- a/test/Data/YamlSpec.hs
+++ b/test/Data/YamlSpec.hs
@@ -15,11 +15,11 @@
 import qualified Control.Monad.Trans.Resource as C
 import qualified Data.Conduit.List as CL
 
-import System.Directory
 import Control.Monad
 import Control.Exception (try, SomeException)
 import Test.Hspec
-import Test.Hspec.Expectations.Contrib
+import Data.Either.Compat
+import Test.Mockery.Directory
 
 import qualified Data.Yaml as D
 import Data.Yaml (object, array, (.=))
@@ -140,7 +140,10 @@
 
     it "aliases in keys #49" caseIssue49
 
+    it "serialization of +123 #64" $ do
+        D.decode (D.encode ("+123" :: String)) `shouldBe` Just ("+123" :: String)
 
+
 specialStrings :: [T.Text]
 specialStrings =
     [ "fo\"o"
@@ -237,26 +240,17 @@
     yamlString = "foo: bar\nbaz:\n - bin1\n - bin2\n"
     yamlBS = B8.pack yamlString
 
-removeFile' :: FilePath -> IO ()
-removeFile' fp = do
-    x <- doesFileExist fp
-    when x $ removeFile fp
-
 caseEncodeDecodeFile :: Assertion
-caseEncodeDecodeFile = do
-    removeFile' tmpPath
+caseEncodeDecodeFile = withFile "" $ \tmpPath -> do
     eList <- C.runResourceT $ Y.decodeFile filePath C.$$ CL.consume
     C.runResourceT $ CL.sourceList eList C.$$ Y.encodeFile tmpPath
     eList2 <- C.runResourceT $ Y.decodeFile filePath C.$$ CL.consume
     map MyEvent eList @=? map MyEvent eList2
   where
     filePath = "test/largest-string.yaml"
-    tmpPath = "tmp.yaml"
 
 caseInterleave :: Assertion
-caseInterleave = do
-    removeFile' tmpPath
-    removeFile' tmpPath2
+caseInterleave = withFile "" $ \tmpPath -> withFile "" $ \tmpPath2 -> do
     () <- C.runResourceT $ Y.decodeFile filePath C.$$ Y.encodeFile tmpPath
     () <- C.runResourceT $ Y.decodeFile tmpPath C.$$ Y.encodeFile tmpPath2
     f1 <- readFile tmpPath
@@ -264,8 +258,6 @@
     f1 @=? f2
   where
     filePath = "test/largest-string.yaml"
-    tmpPath = "tmp.yaml"
-    tmpPath2 = "tmp2.yaml"
 
 caseDecodeInvalidDocument :: Assertion
 caseDecodeInvalidDocument = do
@@ -308,8 +300,7 @@
     out @?= Just sample
 
 caseEncodeDecodeFileData :: Assertion
-caseEncodeDecodeFileData = do
-    let fp = "tmp.yaml"
+caseEncodeDecodeFileData = withFile "" $ \fp -> do
     D.encodeFile fp sample
     out <- D.decodeFile fp
     out @?= Just sample
diff --git a/yaml.cabal b/yaml.cabal
--- a/yaml.cabal
+++ b/yaml.cabal
@@ -1,5 +1,5 @@
 name:            yaml
-version:         0.8.11
+version:         0.8.12
 license:         BSD3
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>, Anton Ageev <antage@gmail.com>,Kirill Simonov 
@@ -114,9 +114,7 @@
                      Data.Yaml.IncludeSpec
     cpp-options:     -DTEST
     build-depends:   hspec >= 1.3
-                   , hspec-expectations
                    , HUnit
-                   , directory
                    , base >= 4 && < 5
                    , transformers >= 0.1
                    , bytestring >= 0.9.1.4
@@ -128,6 +126,8 @@
                    , vector
                    , resourcet
                    , aeson-qq
+                   , mockery
+                   , base-compat
     ghc-options:     -Wall
 
 source-repository head