diff --git a/src/charset.c b/src/charset.c
index 0535d4c..cc02563 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -1218,6 +1218,8 @@
     if ((int)vcol == width1 - 1)
 	return TRUE;
     width2 = width1 + win_col_off2(wp);
+    if (width2 <= 0)
+	return FALSE;
     return ((vcol - width1) % width2 == width2 - 1);
 }
 #endif /* FEAT_MBYTE */