From 8c1f67de8dfb3179db38877ee9b32ce7416dd596 Mon Sep 17 00:00:00 2001
From: Reini Urban <reini.urban@gmail.com>
Date: Tue, 25 Feb 2025 12:09:55 +0100
Subject: [PATCH] outdxf: fix dxf_classes_write with no classes

Fixes GH #1068
---
 src/out_dxf.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/out_dxf.c b/src/out_dxf.c
index 23cd3d051..cbe39afb7 100644
--- a/src/out_dxf.c
+++ b/src/out_dxf.c
@@ -3808,8 +3808,9 @@ dwg_write_dxf (Bit_Chain *restrict dat, Dwg_Data *restrict dwg)
       if ((dat->from_version >= R_13b1 && dwg->num_classes)
           || dat->version >= R_2000)
         {
-          if (dxf_classes_write (dat, dwg) >= DWG_ERR_CRITICAL)
-            goto fail;
+          if (dwg->num_classes) // GH #1068
+            if (dxf_classes_write (dat, dwg) >= DWG_ERR_CRITICAL)
+              goto fail;
         }
       SINCE (R_2_0)
       {