diff --git a/src/textprop.c b/src/textprop.c
index 2d7567c..f219b92 100644
--- a/src/textprop.c
+++ b/src/textprop.c
@@ -1240,9 +1240,12 @@
     if (line == NULL)
 	return;
     mch_memmove(line, newp, len);
-    l = oldproplen * sizeof(textprop_T);
-    mch_memmove(line + len, props, l);
-    len += l;
+    if (oldproplen > 0)
+    {
+	l = oldproplen * sizeof(textprop_T);
+	mch_memmove(line + len, props, l);
+	len += l;
+    }
 
     for (i = 0; i < count - 1; ++i)
 	if (prop_lines[i] != NULL)