diff --git a/src/kiri-mode/fdm/export.js b/src/kiri-mode/fdm/export.js
index 8fc21d5f..92eab23c 100644
--- a/src/kiri-mode/fdm/export.js
+++ b/src/kiri-mode/fdm/export.js
@@ -249,30 +249,47 @@ FDM.export = function(print, online, ondone, ondebug) {
         append(arg.join(''));
     }
 
-    append(`; Generated by Kiri:Moto ${kiri.version}`);
-    append(`; ${new Date().toString()}`);
-    appendSub("; Bed left:{left} right:{right} top:{top} bottom:{bottom}");
-    append(`; Bed type: ${bedType}`);
-    append(`; Target: ${filter[mode]}`);
-    // inject thumbnail preview
-    if (exportThumb && worker.snap) {
-        let { width, height, url } = worker.snap;
-        let data = url.substring(url.indexOf(',') + 1);
-        append(`; thumbnail begin ${width} ${height} ${data.length}`);
-        for (let i=0; i<data.length; i += 78) {
-            append(`; ${data.substring(i, i + 78)}`);
+    function preamble() {
+        append(`; Generated by Kiri:Moto ${kiri.version}`);
+        append(`; ${new Date().toString()}`);
+        appendSub("; Bed left:{left} right:{right} top:{top} bottom:{bottom}");
+        append(`; Bed type: ${bedType}`);
+        append(`; Target: ${filter[mode]}`);
+        // inject thumbnail preview
+        if (exportThumb && worker.snap) {
+            let { width, height, url } = worker.snap;
+            let data = url.substring(url.indexOf(',') + 1);
+            append(`; thumbnail begin ${width} ${height} ${data.length}`);
+            for (let i=0; i<data.length; i += 78) {
+                append(`; ${data.substring(i, i + 78)}`);
+            }
+            append('; thumbnail end');
         }
-        append('; thumbnail end');
+        append("; --- process ---");
+        for (let pk in process) {
+            appendTok("; ", pk, " = ", process[pk]);
+        }
+        append("; --- startup ---");
     }
-    append("; --- process ---");
-    for (let pk in process) {
-        appendTok("; ", pk, " = ", process[pk]);
+
+    // lookg for ";; PREAMBLE <MODE>" comment
+    let pre = 0;
+    let gcpre = [];
+    for (let line of device.gcodePre) {
+        line = line.trim();
+        if (line.indexOf(";; PREAMBLE ") === 0) {
+            if (line === ';; PREAMBLE OFF') pre = 1;
+            if (line === ';; PREAMBLE END') pre = 2;
+        } else {
+            gcpre.push(line);
+        }
     }
-    append("; --- startup ---");
+
+    if (pre === 0) preamble();
+
     let t0 = false;
     let t1 = false;
-    for (let i=0; i<device.gcodePre.length; i++) {
-        let line = device.gcodePre[i];
+    for (let line of gcpre) {
         if (line.indexOf('T0') === 0) t0 = true; else
         if (line.indexOf('T1') === 0) t1 = true; else
         if (line.indexOf('M82') === 0) {
@@ -320,6 +337,8 @@ FDM.export = function(print, online, ondone, ondebug) {
         }
     }
 
+    if (pre === 2) preamble();
+
     function dwell(ms) {
         time += ms/1000;
         // break up dwell times over 4s because of