diff --git a/extlib/libdxfrw b/extlib/libdxfrw
index 8f95895..3475a9b 160000
--- a/extlib/libdxfrw
+++ b/extlib/libdxfrw
@@ -1 +1 @@
-Subproject commit 8f958955f54668c142ded760dc951ffd16d9c71b
+Subproject commit 3475a9bf811afddde7d0638fbcc2b0200d542b07
diff --git a/src/exportvector.cpp b/src/exportvector.cpp
index aa8fed1..5ab335d 100644
--- a/src/exportvector.cpp
+++ b/src/exportvector.cpp
@@ -129,6 +129,10 @@ public:
             hStyle hs = { e->kind };
             polyline = {};
             assignEntityDefaults(&polyline, hs);
+
+            if(!(EXACT(start->pos.z == 0.0) && EXACT(next->pos.z == 0.0))) {
+                polyline.flags |= 8 /* 3d polyline */;
+            }
             polyline.vertlist.push_back(
                 new DRW_Vertex(start->pos.x, start->pos.y, start->pos.z, 0.0));
             polyline.vertlist.push_back(
@@ -136,6 +140,9 @@ public:
         };
 
         auto nextFunc = [&](PolylineBuilder::Vertex *next, PolylineBuilder::Edge *e) {
+            if(!EXACT(next->pos.z == 0.0)) {
+                polyline.flags |= 8 /* 3d polyline */;
+            }
             polyline.vertlist.push_back(
                 new DRW_Vertex(next->pos.x, next->pos.y, next->pos.z, 0.0));
         };