diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4c8eafd..f297747 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -30,6 +30,7 @@ For major (breaking) changes - version 3 and 2 see end of page.
 
 | Version        | Date           | Comment  |
 | -------------- | -------------- | -------- |
+| 4.19.0         | 2020-01-12     | `osInfo()` added uefi |
 | 4.18.3         | 2020-01-10     | `fsSize()` fix excluding loop/snap devices |
 | 4.18.2         | 2020-01-10     | `memLayout()` fix memsize linux (modules >= 32 GB) |
 | 4.18.1         | 2020-01-07     | updated docs |
diff --git a/README.md b/README.md
index fa31145..94b7987 100644
--- a/README.md
+++ b/README.md
@@ -98,13 +98,13 @@ si.cpu()
 
 (last 7 major and minor version releases)
 
+- Version 4.19.0: `osInfo()` added uefi (OS uses UEFI during startup)
 - Version 4.18.0: `networkInterfaces()` added dhcp for mac os, added dhcp linux fallback
 - Version 4.17.0: `networkInterfaces()` added dhcp, dnsSuffix, ieee8021xAuth, ieee8021xState
 - Version 4.16.0: `networkGatewayDefault()` added
 - Version 4.15.0: `cpu()` added governor (linux)
 - Version 4.14.0: `processes()` added process path and params
 - Version 4.13.0: `networkConnections()` added PID, process
-- Version 4.12.0: `networkInterfaces()` added property virtual
 - ...
 
 You can find all changes here: [detailed changelog][changelog-url]
@@ -303,6 +303,7 @@ I also created a nice little command line tool called [mmon][mmon-github-url]  (
 | | serial | X | X | X | X |   | OS/Host serial number |
 | | build | X |   | X | X |   | OS build version |
 | | servicepack | | | | X |   | service pack version |
+| | uefi | X | X | X | X |   | OS started via UEFI |
 | si.uuid(cb) | {...} | X | X | X | X | X | object of several UUIDs |
 | | os | X | X | X | X |  | os specific UUID |
 | si.versions(cb) | {...} | X | X | X | X | X | version information (kernel, ssl, node, ...) |
diff --git a/docs/history.html b/docs/history.html
index d2f12a7..93306e3 100644
--- a/docs/history.html
+++ b/docs/history.html
@@ -51,9 +51,9 @@
               </ul>
               <h4>Breaking Changes</h4>
               <ul>
-                <li><span class="code">networkStats()</span>: will provide an **array** of stats for all given interfaces. In previous versions only one interface was provided as a parameter. Pass '*' for all interfaces</li>
+                <li><span class="code">networkStats()</span>: will provide an <strong>array</strong> of stats for all given interfaces. In previous versions only one interface was provided as a parameter. Pass '*' for all interfaces</li>
                 <li><span class="code">networkStats()</span>: <span class="code">rx</span> and <span class="code">tx</span> changed to <span class="code">rx_bytes</span> and <span class="code">tx_bytes</span></li>
-                <li><span class="code">dockerContainerStats()</span> will provide an **array** of stats for all given docker containers. In previous versions only one interface was provided as a parameter. Pass '*' for all docker containers</li>
+                <li><span class="code">dockerContainerStats()</span> will provide an <strong>array</strong> of stats for all given docker containers. In previous versions only one interface was provided as a parameter. Pass '*' for all docker containers</li>
               </ul>
               <h4>Other Changes</h4>
               <ul>
@@ -65,7 +65,7 @@
                 <li><span class="code">networkStats()</span> added <span class="code">operstate</span>, <span class="code">type</span>, <span class="code">duplex</span>, <span class="code">mtu</span>, <span class="code">speed</span>, <span class="code">carrierChanges</span></li>
                 <li>added TypeScript definitions </li>
               </ul>
-              <p>Be aware**, that the new version 4.x is **NOT fully backward compatible** to version 3.x ...</p>
+              <p><strong>Be aware</strong>, that the new version 4.x is <strong>NOT fully backward compatible</strong> to version 3.x ...</p>
 
               <h3>Major (breaking) Changes - Version 3</h3>
               <ul>
@@ -83,6 +83,11 @@
                   </tr>
                 </thead>
                 <tbody>
+                  <tr>
+                    <th scope="row">4.19.0</th>
+                    <td>2020-01-12</td>
+                    <td><span class="code">osInfo()</span> uefi (OS uses UEFI on startup)</td>
+                  </tr>
                   <tr>
                     <th scope="row">4.18.3</th>
                     <td>2020-01-10</td>
diff --git a/docs/index.html b/docs/index.html
index 18b0625..858ce58 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -168,7 +168,7 @@
       <img class="logo" src="assets/logo.png">
       <div class="title">systeminformation</div>
       <div class="subtitle"><span id="typed"></span></div>
-      <div class="version">Current Version: <span id="version">4.18.3</span></div>
+      <div class="version">Current Version: <span id="version">4.19.0</span></div>
       <button class="btn btn-light" onclick="location.href='https://github.com/sebhildebrandt/systeminformation'">View on Github <i class=" fab fa-github"></i></button>
     </div>
     <div class="down">
diff --git a/docs/os.html b/docs/os.html
index 5cc62a6..ca1b442 100644
--- a/docs/os.html
+++ b/docs/os.html
@@ -195,6 +195,16 @@
                     <td></td>
                     <td>service pack version</td>
                   </tr>
+                  <tr>
+                    <td></td>
+                    <td>uefi</td>
+                    <td>X</td>
+                    <td>X</td>
+                    <td>X</td>
+                    <td>X</td>
+                    <td></td>
+                    <td>OS uses UEFI on startup</td>
+                  </tr>
                   <tr>
                     <td>si.uuid(cb)</td>
                     <td>{...}</td>
diff --git a/lib/index.d.ts b/lib/index.d.ts
index addf9c0..f06d208 100644
--- a/lib/index.d.ts
+++ b/lib/index.d.ts
@@ -203,6 +203,7 @@ export namespace Systeminformation {
     serial: string;
     build: string;
     servicepack: string;
+    uefi: boolean;
   }
 
   interface UuidData {
diff --git a/lib/osinfo.js b/lib/osinfo.js
index 5f1b72b..85ae086 100644
--- a/lib/osinfo.js
+++ b/lib/osinfo.js
@@ -180,7 +180,8 @@ function osInfo(callback) {
         logofile: '',
         serial: '',
         build: '',
-        servicepack: ''
+        servicepack: '',
+        uefi: false
       };
 
       if (_linux) {
@@ -214,19 +215,22 @@ function osInfo(callback) {
           result.codename = codename;
           result.codepage = util.getCodepage();
           result.build = (release.BUILD_ID || '').replace(/"/g, '').trim();
-          uuid().then(data => {
-            result.serial = data.os;
-            if (callback) {
-              callback(result);
-            }
-            resolve(result);
+          isUefiLinux().then(uefi => {
+            result.uefi = uefi;
+            uuid().then(data => {
+              result.serial = data.os;
+              if (callback) {
+                callback(result);
+              }
+              resolve(result);
+            });
           });
           //}
         });
       }
       if (_freebsd || _openbsd || _netbsd) {
 
-        exec('sysctl kern.ostype kern.osrelease kern.osrevision kern.hostuuid', function (error, stdout) {
+        exec('sysctl kern.ostype kern.osrelease kern.osrevision kern.hostuuid machdep.bootmethod', function (error, stdout) {
           if (!error) {
             let lines = stdout.toString().split('\n');
             result.distro = util.getValue(lines, 'kern.ostype');
@@ -235,6 +239,7 @@ function osInfo(callback) {
             result.serial = util.getValue(lines, 'kern.uuid');
             result.codename = '';
             result.codepage = util.getCodepage();
+            result.uefi = util.getValue(lines, 'machdep.bootmethod').toLowerCase().indexOf('uefi') >= 0;
           }
           if (callback) {
             callback(result);
@@ -265,7 +270,7 @@ function osInfo(callback) {
           result.codename = (result.release.indexOf('10.13') > -1 ? 'macOS High Sierra' : result.codename);
           result.codename = (result.release.indexOf('10.14') > -1 ? 'macOS Mojave' : result.codename);
           result.codename = (result.release.indexOf('10.15') > -1 ? 'macOS Catalina' : result.codename);
-
+          result.uefi = true;
           result.codepage = util.getCodepage();
           if (callback) {
             callback(result);
@@ -294,10 +299,13 @@ function osInfo(callback) {
             result.build = util.getValue(lines, 'BuildNumber', '=').trim();
             result.servicepack = util.getValue(lines, 'ServicePackMajorVersion', '=').trim() + '.' + util.getValue(lines, 'ServicePackMinorVersion', '=').trim();
             result.codepage = util.getCodepage();
-            if (callback) {
-              callback(result);
-            }
-            resolve(result);
+            isUefiWindows().then(uefi => {
+              result.uefi = uefi;
+              if (callback) {
+                callback(result);
+              }
+              resolve(result);
+            });
           });
         } catch (e) {
           if (callback) { callback(result); }
@@ -310,6 +318,35 @@ function osInfo(callback) {
 
 exports.osInfo = osInfo;
 
+function isUefiLinux() {
+  return new Promise((resolve) => {
+    process.nextTick(() => {
+      fs.stat('/sys/firmware/efi', function (err) {
+        if (!err) {
+          resolve(true);
+        }
+        else {
+          resolve(false);
+        }
+      });
+    });
+  });
+}
+
+function isUefiWindows() {
+  return new Promise((resolve) => {
+    process.nextTick(() => {
+      exec('%windir%\\Panther\\setupact.log | findstr "Detected boot environment" ', util.execOptsWin, function (error, stdout) {
+        if (!error) {
+          const line = stdout.toString().split('\n\r')[0];
+          resolve(line.toLowerCase().indexOf('uefi') >= 0);
+        }
+        resolve(false);
+      });
+    });
+  });
+}
+
 function versions(callback) {
   return new Promise((resolve) => {
     process.nextTick(() => {