diff --git a/src/unix/System/Terminal.hsc b/src/unix/System/Terminal.hsc
index b8ab1b52d2..e17b35ae5d 100644
--- a/src/unix/System/Terminal.hsc
+++ b/src/unix/System/Terminal.hsc
@@ -28,12 +28,12 @@ foreign import ccall "sys/ioctl.h ioctl"
 
 getTerminalWidth :: IO (Maybe Int)
 getTerminalWidth =
-    alloca $ \p -> do	
-        errno <- ioctl (#const STDOUT_FILENO) (#const TIOCGWINSZ) p	
-        if errno < 0	
-        then return Nothing	
-        else do	
-            WindowWidth w <- peek p	
+    alloca $ \p -> do
+        errno <- ioctl (#const STDOUT_FILENO) (#const TIOCGWINSZ) p
+        if errno < 0
+        then return Nothing
+        else do
+            WindowWidth w <- peek p
             return . Just . fromIntegral $ w
 
 fixCodePage :: x -> y -> a -> a