diff --git a/src/testdir/test_filetype.vim b/src/testdir/test_filetype.vim
index d8ddeff..eba95cf 100644
--- a/src/testdir/test_filetype.vim
+++ b/src/testdir/test_filetype.vim
@@ -313,7 +313,6 @@
     \ 'lotos': ['file.lot', 'file.lotos'],
     \ 'lout': ['file.lou', 'file.lout'],
     \ 'lpc': ['file.lpc', 'file.ulpc'],
-    \ 'lprolog': ['file.sig'],
     \ 'lsl': ['file.lsl'],
     \ 'lss': ['file.lss'],
     \ 'lua': ['file.lua', 'file.rockspec', 'file.nse'],
@@ -1760,4 +1759,59 @@
   filetype off
 endfunc
 
+func Test_sig_file()
+  filetype on
+
+  call writefile(['this is neither Lambda Prolog nor SML'], 'Xfile.sig')
+  split Xfile.sig
+  call assert_equal('', &filetype)
+  bwipe!
+
+  " Test dist#ft#FTsig()
+
+  let g:filetype_sig = 'sml'
+  split Xfile.sig
+  call assert_equal('sml', &filetype)
+  bwipe!
+  unlet g:filetype_sig
+
+  " Lambda Prolog
+
+  call writefile(['sig foo.'], 'Xfile.sig')
+  split Xfile.sig
+  call assert_equal('lprolog', &filetype)
+  bwipe!
+
+  call writefile(['/* ... */'], 'Xfile.sig')
+  split Xfile.sig
+  call assert_equal('lprolog', &filetype)
+  bwipe!
+
+  call writefile(['% ...'], 'Xfile.sig')
+  split Xfile.sig
+  call assert_equal('lprolog', &filetype)
+  bwipe!
+
+  " SML signature file
+
+  call writefile(['signature FOO ='], 'Xfile.sig')
+  split Xfile.sig
+  call assert_equal('sml', &filetype)
+  bwipe!
+
+  call writefile(['structure FOO ='], 'Xfile.sig')
+  split Xfile.sig
+  call assert_equal('sml', &filetype)
+  bwipe!
+
+  call writefile(['(* ... *)'], 'Xfile.sig')
+  split Xfile.sig
+  call assert_equal('sml', &filetype)
+  bwipe!
+
+  call delete('Xfile.sig')
+  filetype off
+endfunc
+
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/version.c b/src/version.c
index 11fd817..116113b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -736,6 +736,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    12,
+/**/
     11,
 /**/
     10,