diff --git a/src/sys/es/fan/Env.js b/src/sys/es/fan/Env.js
index ec53107a0..f9d2ac6a8 100644
--- a/src/sys/es/fan/Env.js
+++ b/src/sys/es/fan/Env.js
@@ -24,7 +24,7 @@ class Env extends Obj {
     this.#vars.caseInsensitive(true);
     this.#props = Map.make(Str.type$, Str.type$);
 
-    const vars = ((typeof globalThis.fan$env) === 'undefined') ? {} : globalThis.fan$env;
+    const vars = ((typeof js.fan$env) === 'undefined') ? {} : js.fan$env;
     this.__loadVars(vars);
 
     this.#out = new ConsoleOutStream();
@@ -37,7 +37,7 @@ class Env extends Obj {
     // set some pre-defined vars
     if (Env.__isNode()) {
       this.#vars.set("os.name", this.os());
-      this.#vars.set("os.version", Env.__node().os.version());
+      this.#vars.set("os.version", Env.__node()?.os?.version());
     }
 
     for (let i=0; i<keys.length; ++i) {
@@ -106,13 +106,13 @@ class Env extends Obj {
   javaVersion() { return 0; }
 
   os() { 
-    let p = Env.__node().os.platform();
+    let p = Env.__node()?.os?.platform();
     if (p === "darwin") p = "macosx";
     return p;
   }
 
   arch() {
-    let a = Env.__node().os.arch();
+    let a = Env.__node()?.os?.arch();
     switch (a) {
       case "ia32": a = "x86";
       case "x64":  a = "x86_64";
@@ -139,7 +139,7 @@ class Env extends Obj {
 
   diagnostics() { return Map.make(Str.type$, Obj.type$); }
 
-  host() { return Env.__node().os.hostname(); }
+  host() { return Env.__node()?.os?.hostname(); }
 
   user() { return "unknown"; }
 
@@ -152,7 +152,7 @@ class Env extends Obj {
 
   #win32prompt(msg) {
     // https://github.com/nodejs/node/issues/28243
-    const fs = Env.__node().fs;
+    const fs = Env.__node()?.fs;
     fs.writeSync(1, String(msg));
     let s = '', buf = Buffer.alloc(1);
     while(buf[0] != 10 && buf[0] != 13) {
@@ -165,7 +165,7 @@ class Env extends Obj {
 
   #unixprompt(msg) {
     // https://stackoverflow.com/questions/61394928/get-user-input-through-node-js-console/74250003?noredirect=1#answer-75008198
-    const fs = Env.__node().fs;
+    const fs = Env.__node()?.fs;
     const stdin = fs.openSync("/dev/stdin","rs");
 
     fs.writeSync(process.stdout.fd, msg);
diff --git a/src/sys/es/fan/File.js b/src/sys/es/fan/File.js
index 907040373..bd467eeb4 100644
--- a/src/sys/es/fan/File.js
+++ b/src/sys/es/fan/File.js
@@ -62,8 +62,8 @@ class File extends Obj {
   static os(osPath) {
     if (!Env.__isNode())
       throw Err.make("Must be running on Node JS to create a local file.");
-    const os   = node.os;
-    if (os.platform() == "win32") {
+    const os = node.os;
+    if (os?.platform() == "win32") {
       if (osPath.startsWith("/")) {
         osPath = "file://" + osPath;
       } else if (/^.+:/.test(osPath)) {
@@ -77,7 +77,7 @@ class File extends Obj {
   static osRoots() {
     if (!Env.__isNode())
       throw Err.make("Must be running on Node JS to access the OS roots.");
-    const r = node.os.platform() == "win32"
+    const r = node.os?.platform() == "win32"
       ? "/" + File.__win32Drive() + "/"
       : node.path.parse(process.cwd()).root;
     return List.make(File.type$, [File.make(r, false)]);
diff --git a/src/sys/es/fan/LocalFile.js b/src/sys/es/fan/LocalFile.js
index 3b6e07127..da010d1a2 100644
--- a/src/sys/es/fan/LocalFile.js
+++ b/src/sys/es/fan/LocalFile.js
@@ -38,7 +38,7 @@ class LocalFile extends File {
     // console.log("TODO: normalize windows path: " + instance.m_uri_str);
     instance.#node_os_path = uri.toStr();
 
-    if (os.platform == "win32" && uri.isPathAbs()) {
+    if (os?.platform == "win32" && uri.isPathAbs()) {
       let uriStr = uri.toStr();
       if (!uri.isAbs()) {
         // ensure the uri has file scheme
diff --git a/src/sys/es/fan/ZipSupport.js b/src/sys/es/fan/ZipSupport.js
index 0e4563feb..75cf12609 100644
--- a/src/sys/es/fan/ZipSupport.js
+++ b/src/sys/es/fan/ZipSupport.js
@@ -1152,7 +1152,7 @@ class YazlZipFile {
     // size of the central directory                                                  8 bytes
     yazl.writeUInt64LE(zip64EocdrBuffer, sizeOfCentralDirectory, 40);
     // offset of start of central directory with respect to the starting disk number  8 bytes
-    writeUInt64LE(zip64EocdrBuffer, this.offsetOfStartOfCentralDirectory, 48);
+    yazl.writeUInt64LE(zip64EocdrBuffer, this.offsetOfStartOfCentralDirectory, 48);
     // zip64 extensible data sector                                                   (variable size)
     // nothing in the zip64 extensible data sector