1 files changed, 2 insertions, 0 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index 85b9eae36d1..2aceb89c003 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -21009,6 +21009,8 @@ maybe_produce_line_number (struct it *it)
   struct glyph *p = it->glyph_row ? it->glyph_row->glyphs[TEXT_AREA] : NULL;
   short *u = it->glyph_row ? &it->glyph_row->used[TEXT_AREA] : NULL;
 
+  eassert (it->glyph_row == NULL || it->glyph_row->used[TEXT_AREA] == 0);
+
   for ( ; g < e; g++)
     {
       it->current_x += g->pixel_width;