diff --git a/packages/node_modules/@node-red/runtime/lib/storage/localfilesystem/projects/index.js b/packages/node_modules/@node-red/runtime/lib/storage/localfilesystem/projects/index.js
index 674b380e6..82c1f8d39 100644
--- a/packages/node_modules/@node-red/runtime/lib/storage/localfilesystem/projects/index.js
+++ b/packages/node_modules/@node-red/runtime/lib/storage/localfilesystem/projects/index.js
@@ -56,8 +56,9 @@ function init(_settings, _runtime) {
 
     if (settings.flowFile) {
         flowsFile = settings.flowFile;
-        // handle Unix and Windows "C:\"
-        if ((flowsFile[0] == "/") || (flowsFile[1] == ":")) {
+        // handle Unix and Windows "C:\" and Windows "\\" for UNC.
+        if (fspath.isAbsolute(flowsFile)) {
+        //if (((flowsFile[0] == "\\") && (flowsFile[1] == "\\")) || (flowsFile[0] == "/") || (flowsFile[1] == ":")) {
             // Absolute path
             flowsFullPath = flowsFile;
         } else if (flowsFile.substring(0,2) === "./") {
diff --git a/packages/node_modules/@node-red/runtime/lib/storage/localfilesystem/util.js b/packages/node_modules/@node-red/runtime/lib/storage/localfilesystem/util.js
index 267f8c933..b18c80643 100644
--- a/packages/node_modules/@node-red/runtime/lib/storage/localfilesystem/util.js
+++ b/packages/node_modules/@node-red/runtime/lib/storage/localfilesystem/util.js
@@ -15,6 +15,7 @@
  **/
 
 var fs = require('fs-extra');
+var fspath = require('path');
 var when = require('when');
 var nodeFn = require('when/node/function');
 
@@ -79,25 +80,31 @@ module.exports = {
      * the write hits disk.
      */
      writeFile: function(path,content,backupPath) {
-         if (backupPath) {
+        if (backupPath) {
             if (fs.existsSync(path)) {
                 fs.renameSync(path,backupPath);
             }
         }
         return when.promise(function(resolve,reject) {
-            var stream = fs.createWriteStream(path);
-            stream.on('open',function(fd) {
-                stream.write(content,'utf8',function() {
-                    fs.fsync(fd,function(err) {
-                        if (err) {
-                            log.warn(log._("storage.localfilesystem.fsync-fail",{path: path, message: err.toString()}));
-                        }
-                        stream.end(resolve);
+            fs.ensureDir(fspath.dirname(path), (err)=>{
+                if (err) {
+                    reject(err);
+                    return;
+                }
+                var stream = fs.createWriteStream(path);
+                stream.on('open',function(fd) {
+                    stream.write(content,'utf8',function() {
+                        fs.fsync(fd,function(err) {
+                            if (err) {
+                                log.warn(log._("storage.localfilesystem.fsync-fail",{path: path, message: err.toString()}));
+                            }
+                            stream.end(resolve);
+                        });
                     });
                 });
-            });
-            stream.on('error',function(err) {
-                reject(err);
+                stream.on('error',function(err) {
+                    reject(err);
+                });
             });
         });
      },
diff --git a/test/unit/@node-red/runtime/lib/storage/localfilesystem/index_spec.js b/test/unit/@node-red/runtime/lib/storage/localfilesystem/index_spec.js
index 464afa7e0..acfe3db43 100644
--- a/test/unit/@node-red/runtime/lib/storage/localfilesystem/index_spec.js
+++ b/test/unit/@node-red/runtime/lib/storage/localfilesystem/index_spec.js
@@ -19,6 +19,7 @@ var fs = require('fs-extra');
 var path = require('path');
 var sinon = require('sinon');
 var NR_TEST_UTILS = require("nr-test-utils");
+var process = require("process");
 
 var localfilesystem = NR_TEST_UTILS.require("@node-red/runtime/lib/storage/localfilesystem");
 var log = NR_TEST_UTILS.require("@node-red/util").log;
@@ -474,4 +475,44 @@ describe('storage/localfilesystem', function() {
             done(err);
         });
     });
+
+    it('should handle flow file in random unc path and non-existent subfolder',function(done) {
+        // only test on win32
+        if (process.platform !== 'win32') {
+          console.log('skipped test as not win32');
+          done();
+          return;
+        }
+        
+        // get a real windows path
+        var flowFile = path.win32.resolve(userDir+'/some/random/path');
+        var rootdir = path.win32.resolve(userDir+'/some');
+        // make it into a local UNC path
+        flowFile = flowFile.replace('C:\\', '\\\\localhost\\c$\\');
+        localfilesystem.init({userDir:userDir, flowFile:flowFile}, mockRuntime).then(function() {
+            fs.existsSync(flowFile).should.be.false();
+            localfilesystem.saveFlows(testFlow).then(function() {
+                fs.existsSync(flowFile).should.be.true();
+                localfilesystem.getFlows().then(function(flows) {
+                    flows.should.eql(testFlow);
+                    // cleanup
+                    fs.removeSync(rootdir);
+                    done();
+                }).catch(function(err) {
+                    // cleanup
+                    fs.removeSync(rootdir);
+                    done(err);
+                });
+            }).catch(function(err) {
+                // cleanup
+                fs.removeSync(rootdir);
+                done(err);
+            });
+        }).catch(function(err) {
+            // cleanup
+            fs.removeSync(rootdir);
+            done(err);
+        });
+    });
+    
 });