diff --git a/src/diff.c b/src/diff.c
index 00ccdb6..df3dea0 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -1466,7 +1466,7 @@
     curwin = wp;
     curbuf = curwin->w_buffer;
     ++curbuf_lock;
-    set_option_value((char_u *)"diff", (long)value, NULL, OPT_LOCAL);
+    set_option_value_give_err((char_u *)"diff", (long)value, NULL, OPT_LOCAL);
     --curbuf_lock;
     curwin = old_curwin;
     curbuf = curwin->w_buffer;