diff --git a/System/Posix/Files.hsc b/System/Posix/Files.hsc
index c8b5ddf3fd1196b10580e4ec9c28aa63bd807f14..1822294cb71b1fd601fa23c34a9f1d8c35894976 100644
--- a/System/Posix/Files.hsc
+++ b/System/Posix/Files.hsc
@@ -1,6 +1,8 @@
 #ifdef __GLASGOW_HASKELL__
 {-# LANGUAGE Trustworthy #-}
 #endif
+{-# LANGUAGE CApiFFI #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  System.Posix.Files
@@ -420,7 +422,7 @@ setFileSize file off =
   withFilePath file $ \s ->
     throwErrnoPathIfMinus1_ "setFileSize" file (c_truncate s off)
 
-foreign import ccall unsafe "truncate"
+foreign import capi unsafe "HsUnix.h truncate"
   c_truncate :: CString -> COff -> IO CInt
 
 -- -----------------------------------------------------------------------------
diff --git a/System/Posix/Files/ByteString.hsc b/System/Posix/Files/ByteString.hsc
index 80f0beabbd4fa7cae9a1e3a38876ffd163ae5ec8..cb68668c1c520455a012548686f727144fb9ec8f 100644
--- a/System/Posix/Files/ByteString.hsc
+++ b/System/Posix/Files/ByteString.hsc
@@ -1,6 +1,8 @@
 #ifdef __GLASGOW_HASKELL__
 {-# LANGUAGE Trustworthy #-}
 #endif
+{-# LANGUAGE CApiFFI #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  System.Posix.Files.ByteString
@@ -420,7 +422,7 @@ setFileSize file off =
   withFilePath file $ \s ->
     throwErrnoPathIfMinus1_ "setFileSize" file (c_truncate s off)
 
-foreign import ccall unsafe "truncate"
+foreign import capi unsafe "HsUnix.h truncate"
   c_truncate :: CString -> COff -> IO CInt
 
 -- -----------------------------------------------------------------------------
diff --git a/changelog.md b/changelog.md
index c481922fcc33637136f001c7d6497eb75dc7d718..66caaeba3a4e449dc47bbe24c8262bb93f33ab7e 100644
--- a/changelog.md
+++ b/changelog.md
@@ -12,6 +12,8 @@
     convention
   * Fix potential type-mismatch in `telldir`/`seekdir` FFI imports
 
+  * Use CAPI FFI import for `truncate` to make sure the LFS-version is used.
+
 ## 2.7.0.1  *Mar 2014*
 
   * Bundled with GHC 7.8.1
diff --git a/configure.ac b/configure.ac
index 41274dc039d86186c014dad2125e273e3ce2a740..c10bf8981cbf5cdd2ec0a298886aba6ec0c5f967 100644
--- a/configure.ac
+++ b/configure.ac
@@ -18,6 +18,9 @@ AC_C_CONST
 
 dnl ** Enable large file support.  NB. do this before testing the type of
 dnl    off_t, because it will affect the result of that test.
+dnl
+dnl WARNING: It's essential this check agrees with HsBaseConfig.h as otherwise
+dnl          the definitions of COff/coff_t don't line up
 AC_SYS_LARGEFILE
 
 AC_CHECK_HEADERS([dirent.h fcntl.h grp.h limits.h pwd.h signal.h string.h])