diff --git a/src/register.c b/src/register.c
index d604bae..03f7f4e 100644
--- a/src/register.c
+++ b/src/register.c
@@ -1474,7 +1474,7 @@
     {
 	int s = bd->textlen + bd->endspaces;
 
-	while (VIM_ISWHITE(*(bd->textstart + s - 1)) && s > 0)
+	while (s > 0 && VIM_ISWHITE(*(bd->textstart + s - 1)))
 	{
 	    s = s - (*mb_head_off)(bd->textstart, bd->textstart + s - 1) - 1;
 	    pnew--;
diff --git a/src/testdir/test_visual.vim b/src/testdir/test_visual.vim
index b2beda0..af54615 100644
--- a/src/testdir/test_visual.vim
+++ b/src/testdir/test_visual.vim
@@ -1247,6 +1247,13 @@
   bw!
 endfunc
 
+func Test_visual_block_yank_zy()
+  new
+  " this was reading before the start of the line
+  exe "norm o\<C-T>\<Esc>\<C-V>zy"
+  bwipe!
+endfunc
+
 func Test_visual_block_with_virtualedit()
   CheckScreendump
 
diff --git a/src/version.c b/src/version.c
index 9dcf349..a3efb04 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4219,
+/**/
     4218,
 /**/
     4217,