diff --git a/src/evalfunc.c b/src/evalfunc.c
index 2bbdefc..7c781d8 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -11841,8 +11841,8 @@
 	    if ((syntax_flags & HL_CONCEAL) && curwin->w_p_cole < 3)
 	    {
 		cchar = syn_get_sub_char();
-		if (cchar == NUL && curwin->w_p_cole == 1 && lcs_conceal != NUL)
-		    cchar = lcs_conceal;
+		if (cchar == NUL && curwin->w_p_cole == 1)
+		    cchar = (lcs_conceal == NUL) ? ' ' : lcs_conceal;
 		if (cchar != NUL)
 		{
 # ifdef FEAT_MBYTE
diff --git a/src/testdir/test_syntax.vim b/src/testdir/test_syntax.vim
index 427ed7b..0b1b4e4 100644
--- a/src/testdir/test_syntax.vim
+++ b/src/testdir/test_syntax.vim
@@ -4,6 +4,8 @@
   finish
 endif
 
+source view_util.vim
+
 func GetSyntaxItem(pat)
   let c = ''
   let a = ['a', getreg('a'), getregtype('a')]
@@ -458,3 +460,46 @@
   set redrawtime&
   bwipe!
 endfunc
+
+
+func Test_conceal()
+  if !has('conceal')
+    return
+  endif
+
+  new
+  call setline(1, ['', '123456'])
+  syn match test23 "23" conceal cchar=X
+  syn match test45 "45" conceal
+
+  set conceallevel=0
+  call assert_equal('123456 ', ScreenLines(2, 7)[0])
+  call assert_equal([[0, ''], [0, ''], [0, ''], [0, ''], [0, ''], [0, '']], map(range(1, 6), 'synconcealed(2, v:val)[0:1]'))
+
+  set conceallevel=1
+  call assert_equal('1X 6   ', ScreenLines(2, 7)[0])
+  " FIXME: with conceallevel=1, I would expect that the portion "45" of
+  " the line to be replaced with a space since ":help 'conceallevel'
+  " states that if listchars is not set, then the default replacement
+  " should be a space. But synconcealed() gives an empty string in
+  " the 2nd value of the returned list. Bug?
+  " So for now, the following line is commented out:
+  call assert_equal([[0, ''], [1, 'X'], [1, 'X'], [1, ' '], [1, ' '], [0, '']], map(range(1, 6), 'synconcealed(2, v:val)[0:1]'))
+
+  set conceallevel=1
+  set listchars=conceal:Y
+  call assert_equal([[0, ''], [1, 'X'], [1, 'X'], [1, 'Y'], [1, 'Y'], [0, '']], map(range(1, 6), 'synconcealed(2, v:val)[0:1]'))
+  call assert_equal('1XY6   ', ScreenLines(2, 7)[0])
+
+  set conceallevel=2
+  call assert_match('1X6    ', ScreenLines(2, 7)[0])
+  call assert_equal([[0, ''], [1, 'X'], [1, 'X'], [1, ''], [1, ''], [0, '']], map(range(1, 6), 'synconcealed(2, v:val)[0:1]'))
+
+  set conceallevel=3
+  call assert_match('16     ', ScreenLines(2, 7)[0])
+  call assert_equal([[0, ''], [1, ''], [1, ''], [1, ''], [1, ''], [0, '']], map(range(1, 6), 'synconcealed(2, v:val)[0:1]'))
+
+  syn clear
+  set conceallevel&
+  bw!
+endfunc
diff --git a/src/version.c b/src/version.c
index ab0381c..cb4ac7f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    659,
+/**/
     658,
 /**/
     657,