diff --git a/src/charset.c b/src/charset.c
index 9609299..ebec2cf 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -1152,6 +1152,8 @@
      * First get the normal size, without 'linebreak' or text properties
      */
     size = win_chartabsize(wp, s, vcol);
+    if (*s == NUL)
+	size = 0;  // NUL is not displayed
 
 # ifdef FEAT_PROP_POPUP
     if (cts->cts_has_prop_with_text)