diff --git a/configure.in b/configure.in
index 8e3765c81c3ecfad04b0326480bbb44758928fb9..0043619650f229c71d4a07ed2f7b2cfb70d469af 100644
--- a/configure.in
+++ b/configure.in
@@ -31,7 +31,7 @@ AC_ARG_ENABLE(iphone,
  AS_HELP_STRING(--enable-iphone, compile with iPhone support),
  [if test x$enableval = xyes ; then
    tor_cv_iphone=true
-   CFLAGS="$CFLAGS -D__DARWIN_UINX03 -DIPHONE"
+   CFLAGS="$CFLAGS -D__DARWIN_UNIX03 -DIPHONE"
   fi])
 
 AC_ARG_ENABLE(cell-pool,