diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,13 @@
+0.8.1.0
+-------
+
+* Fix use after free in `createFontMem` #17
+
+0.8.0.0
+-------
+
+* Windows support
+
 0.6.0.0
 ---
 
diff --git a/nanovg.cabal b/nanovg.cabal
--- a/nanovg.cabal
+++ b/nanovg.cabal
@@ -1,5 +1,5 @@
 name:                nanovg
-version:             0.8.0.0
+version:             0.8.1.0
 synopsis:            Haskell bindings for nanovg
 description:         Raw bindings to the OpenGL vector graphics library NanoVG
 homepage:            https://github.com/cocreature/nanovg-hs
@@ -70,7 +70,7 @@
       exposed-modules:
                        NanoVG.Internal.GL3
   build-depends:       base >= 4.8 && <5.0
-                     , bytestring >= 0.10 && < 0.11
+                     , bytestring >= 0.10 && < 0.12
                      , containers >= 0.5 && < 0.7
                      , text >= 1.2 && < 1.3
                      , vector >= 0.11 && < 0.13
diff --git a/src/NanoVG/Internal/FFIHelpers.hs b/src/NanoVG/Internal/FFIHelpers.hs
--- a/src/NanoVG/Internal/FFIHelpers.hs
+++ b/src/NanoVG/Internal/FFIHelpers.hs
@@ -2,11 +2,12 @@
   (withCString
   ,useAsCStringLen'
   ,useAsPtr
-  ,zero
+  ,one
   ,null
   ,bitMask
   ) where
 
+import           Control.Monad ((>=>))
 import           Data.Bits ((.|.))
 import           Data.ByteString hiding (null)
 import qualified Data.Set as S
@@ -14,6 +15,7 @@
 import qualified Data.Text.Encoding as T
 import           Foreign.C.String (CString)
 import           Foreign.C.Types
+import           Foreign.Marshal (copyBytes, mallocBytes)
 import           Foreign.Ptr
 import           Prelude hiding (null)
 
@@ -23,15 +25,27 @@
 
 -- | Wrapper around 'useAsCStringLen' that uses 'CUChar's
 useAsCStringLen' :: ByteString -> ((Ptr CUChar,CInt) -> IO a) -> IO a
-useAsCStringLen' bs f = useAsCStringLen bs (\(ptr,len) -> f (castPtr ptr,fromIntegral len))
+useAsCStringLen' bs f = useAsCStringLen bs ((\(ptr,len) -> return (castPtr ptr,fromIntegral len)) >=> copyCStringLen >=> f)
+  where
+    -- | Copy memory under given pointer to a new address.
+    -- The allocated memory is not garbage-collected and needs to be freed manually later.
+    -- In the case of 'createFontMem' and 'createFontMemAtIndex' (the only places using it)
+    -- it is freed by NanoVG as a part of 'nvgDeleteGL3'.
+    copyCStringLen :: Integral b => (Ptr a, b) -> IO (Ptr a, b)
+    copyCStringLen (from, len) =
+      let intLen = fromIntegral len
+      in do
+        to <- mallocBytes intLen
+        copyBytes to from intLen
+        return (to, len)
 
 -- | Wrapper around 'useAsCStringLen'' that discards the length
 useAsPtr :: ByteString -> (Ptr CUChar -> IO a) -> IO a
 useAsPtr bs f = useAsCStringLen' bs (f . fst)
 
--- | Marshalling helper for a constant zero
-zero :: Num a => (a -> b) -> b
-zero f = f 0
+-- | Marshalling helper for a constant one
+one :: Num a => (a -> b) -> b
+one f = f 1
 
 -- | Marshalling helper for a constant 'nullPtr'
 null :: (Ptr a -> b) -> b
diff --git a/src/NanoVG/Internal/Text.chs b/src/NanoVG/Internal/Text.chs
--- a/src/NanoVG/Internal/Text.chs
+++ b/src/NanoVG/Internal/Text.chs
@@ -105,16 +105,16 @@
 {#fun unsafe nvgCreateFontAtIndex as createFontAtIndex
         {`Context',withCString*`T.Text','withCString.unwrapFileName'*`FileName', `CInt'} -> `Maybe Font'safeFont#}
 
--- | Creates image by loading it from the specified memory chunk.
+-- | Creates font by loading it from the specified memory chunk.
 -- Returns handle to the font.
 {#fun unsafe nvgCreateFontMem as createFontMem
-        {`Context',withCString*`T.Text',useAsCStringLen'*`ByteString'&,zero-`CInt'} -> `Maybe Font'safeFont#}
+        {`Context',withCString*`T.Text',useAsCStringLen'*`ByteString'&,one-`CInt'} -> `Maybe Font'safeFont#}
 
--- | Creates image by loading it from the specified memory chunk.
+-- | Creates font by loading it from the specified memory chunk.
 -- fontIndex specifies which font face to load from a .ttf/.ttc file.
 -- Returns handle to the font.
 {#fun unsafe nvgCreateFontMemAtIndex as createFontMemAtIndex
-        {`Context',withCString*`T.Text',useAsCStringLen'*`ByteString'&,zero-`CInt',`CInt'} -> `Maybe Font'safeFont#}
+        {`Context',withCString*`T.Text',useAsCStringLen'*`ByteString'&,one-`CInt',`CInt'} -> `Maybe Font'safeFont#}
 
 -- | Finds a loaded font of specified name, and returns handle to it, or -1 if the font is not found.
 {#fun unsafe nvgFindFont as findFont