diff --git a/src/parser.js b/src/parser.js
index db10657..d9df31c 100644
--- a/src/parser.js
+++ b/src/parser.js
@@ -398,8 +398,17 @@ class Parser {
       const browserNames = Object.keys(browsers);
       const matchingDefinition = Utils.find(browserNames, name => (this.isBrowser(name, true)));
 
-      if (matchingDefinition !== void 0) {
-        return this.compareVersion(browsers[matchingDefinition]);
+      if (matchingDefinition !== void 0 && !checkTree.OS) {
+        return this.compareBrowserVersion(browsers[matchingDefinition]);
+      }
+
+      if (matchingDefinition !== void 0 && checkTree.OS) {
+        return this.compareBrowserVersion(browsers[matchingDefinition])
+        && this.compareOSVersion(checkTree.OS);
+      }
+
+      if (checkTree.OS) {
+        return this.compareOSVersion(checkTree.OS);
       }
     }
 
@@ -423,39 +432,47 @@ class Parser {
     return browserNameLower === defaultBrowserName;
   }
 
-  compareVersion(version) {
+  compareBrowserVersion(versionToCompare) {
+    const currentBrowserVersion = this.getBrowserVersion();
+    return this.compareVersion(currentBrowserVersion, versionToCompare);
+  }
+
+  compareOSVersion(versionToCompare) {
+    const currentOSVersion = this.getOSVersion();
+    return this.compareVersion(currentOSVersion, versionToCompare);
+  }
+
+  compareVersion = (version, versionToCompare) => {
     let expectedResults = [0];
-    let comparableVersion = version;
+    let comparableVersion = versionToCompare;
     let isLoose = false;
 
-    const currentBrowserVersion = this.getBrowserVersion();
-
-    if (typeof currentBrowserVersion !== 'string') {
+    if (typeof version !== 'string') {
       return void 0;
     }
 
-    if (version[0] === '>' || version[0] === '<') {
-      comparableVersion = version.substr(1);
-      if (version[1] === '=') {
+    if (versionToCompare[0] === '>' || versionToCompare[0] === '<') {
+      comparableVersion = versionToCompare.substr(1);
+      if (versionToCompare[1] === '=') {
         isLoose = true;
-        comparableVersion = version.substr(2);
+        comparableVersion = versionToCompare.substr(2);
       } else {
         expectedResults = [];
       }
-      if (version[0] === '>') {
+      if (versionToCompare[0] === '>') {
         expectedResults.push(1);
       } else {
         expectedResults.push(-1);
       }
-    } else if (version[0] === '=') {
-      comparableVersion = version.substr(1);
-    } else if (version[0] === '~') {
+    } else if (versionToCompare[0] === '=') {
+      comparableVersion = versionToCompare.substr(1);
+    } else if (versionToCompare[0] === '~') {
       isLoose = true;
-      comparableVersion = version.substr(1);
+      comparableVersion = versionToCompare.substr(1);
     }
 
     return expectedResults.indexOf(
-      Utils.compareVersions(currentBrowserVersion, comparableVersion, isLoose),
+      Utils.compareVersions(version, comparableVersion, isLoose),
     ) > -1;
   }
 
diff --git a/test/unit/parser.js b/test/unit/parser.js
index 66036fd..86a2f8a 100644
--- a/test/unit/parser.js
+++ b/test/unit/parser.js
@@ -12,6 +12,9 @@ const edgeParser = new Parser(EDGE_UA, true);
 const FOCUS_UA = 'Mozilla/5.0 (Linux; Android 7.1.1) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Focus/1.2.1 Chrome/59.0.3071.125';
 const focusParser = new Parser(FOCUS_UA, true);
 
+const IPHONE_UA = 'Mozilla/5.0 (iPhone; CPU iPhone OS 14_4 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0 Mobile/15E148 Safari/604.1';
+const iphoneParser = new Parser(IPHONE_UA, true);
+
 test('constructor', (t) => {
   t.truthy(parser instanceof Parser);
 });
@@ -155,8 +158,27 @@ test('Parser.satisfies for versionless UA strings', (t) => {
 test('Parser.satisfies should consider aliases while handling browsers', (t) => {
   t.is(edgeParser.satisfies({ 'Microsoft Edge': '=41.1.35.1' }), true);
   t.is(edgeParser.satisfies({ 'microsoft edge': '=41.1.35.1' }), true);
-  t.is(edgeParser.satisfies({ 'edge': '=41.1.35.1' }), true);
-  t.is(edgeParser.satisfies({ 'Edge': '=41.1.35.1' }), true);
+  t.is(edgeParser.satisfies({ edge: '=41.1.35.1' }), true);
+  t.is(edgeParser.satisfies({ Edge: '=41.1.35.1' }), true);
+});
+
+test('Parser.satisfies should consider OS while handling browsers', (t) => {
+  t.is(parser.satisfies({ macos: { OS: '>=8.0.0' } }), true);
+  t.is(parser.satisfies({ macos: { OS: '>=8.0.0', chrome: '>50' } }), true);
+  t.is(iphoneParser.satisfies({
+    windows: {
+      OS: '>=10',
+    },
+    macos: {
+      OS: '>=10.13',
+    },
+    android: {
+      OS: '>=7',
+    },
+    iOS: {
+      OS: '>=8.4',
+    },
+  }), true);
 });
 
 test('Parser.is should pass', (t) => {