diff --git a/src/spellfile.c b/src/spellfile.c
index 5962a10..7620aff 100644
--- a/src/spellfile.c
+++ b/src/spellfile.c
@@ -5585,10 +5585,12 @@
 
     /*
      * Go through the whole case-folded tree, soundfold each word and put it
-     * in the trie.
+     * in the trie.  Bail out if the tree is empty.
      */
     byts = slang->sl_fbyts;
     idxs = slang->sl_fidxs;
+    if (byts == NULL || idxs == NULL)
+	return FAIL;
 
     arridx[0] = 0;
     curi[0] = 1;
diff --git a/src/testdir/test_spellfile.vim b/src/testdir/test_spellfile.vim
index 43dfad4..28e69bd 100644
--- a/src/testdir/test_spellfile.vim
+++ b/src/testdir/test_spellfile.vim
@@ -1168,4 +1168,16 @@
   delete('Xtest', 'rf')
 enddef
 
+" this was using a NULL pointer
+func Test_mkspell_empty_dic()
+  call writefile(['1'], 'XtestEmpty.dic')
+  call writefile(['SOFOFROM abcd', 'SOFOTO ABCD', 'SAL CIA X'], 'XtestEmpty.aff')
+  mkspell! XtestEmpty.spl XtestEmpty
+
+  call delete('XtestEmpty.dic')
+  call delete('XtestEmpty.aff')
+  call delete('XtestEmpty.spl')
+endfunc
+
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/version.c b/src/version.c
index fe100c8..9e77abc 100644
--- a/src/version.c
+++ b/src/version.c
@@ -732,6 +732,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    240,
+/**/
     239,
 /**/
     238,