diff --git a/dist/index.js b/dist/index.js
index 2176821..ab82125 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -333,7 +333,9 @@ class DotnetCoreInstaller {
                 if (process.env['no_proxy'] != null) {
                     scriptArguments.push(`-ProxyBypassList ${process.env['no_proxy']}`);
                 }
-                scriptArguments.push('-InstallDir', `'${DotnetCoreInstaller.installationDirectoryWindows}'`);
+                if (!process.env['DOTNET_INSTALL_DIR']) {
+                    scriptArguments.push('-InstallDir', `'${DotnetCoreInstaller.installationDirectoryWindows}'`);
+                }
                 // process.env must be explicitly passed in for DOTNET_INSTALL_DIR to be used
                 scriptPath =
                     (yield io.which('pwsh', false)) || (yield io.which('powershell', true));
@@ -349,18 +351,19 @@ class DotnetCoreInstaller {
                 if (this.quality) {
                     this.setQuality(dotnetVersion, scriptArguments);
                 }
-                if (utils_1.IS_LINUX) {
-                    scriptArguments.push('--install-dir', DotnetCoreInstaller.installationDirectoryLinux);
-                }
-                if (utils_1.IS_MAC) {
-                    scriptArguments.push('--install-dir', DotnetCoreInstaller.installationDirectoryMac);
+                if (!process.env['DOTNET_INSTALL_DIR']) {
+                    scriptArguments.push('--install-dir', utils_1.IS_LINUX
+                        ? DotnetCoreInstaller.installationDirectoryLinux
+                        : DotnetCoreInstaller.installationDirectoryMac);
                 }
             }
             const { exitCode, stdout } = yield exec.getExecOutput(`"${scriptPath}"`, scriptArguments, { ignoreReturnCode: true });
             if (exitCode) {
                 throw new Error(`Failed to install dotnet ${exitCode}. ${stdout}`);
             }
-            return this.outputDotnetVersion(dotnetVersion.value, scriptArguments[scriptArguments.length - 1]);
+            return this.outputDotnetVersion(dotnetVersion.value, process.env['DOTNET_INSTALL_DIR']
+                ? process.env['DOTNET_INSTALL_DIR']
+                : scriptArguments[scriptArguments.length - 1]);
         });
     }
     outputDotnetVersion(version, installationPath) {
@@ -523,10 +526,9 @@ run();
 "use strict";
 
 Object.defineProperty(exports, "__esModule", ({ value: true }));
-exports.IS_MAC = exports.IS_LINUX = exports.IS_WINDOWS = void 0;
+exports.IS_LINUX = exports.IS_WINDOWS = void 0;
 exports.IS_WINDOWS = process.platform === 'win32';
 exports.IS_LINUX = process.platform === 'linux';
-exports.IS_MAC = process.platform === 'darwin';
 
 
 /***/ }),
diff --git a/src/installer.ts b/src/installer.ts
index 041b655..dc3c275 100644
--- a/src/installer.ts
+++ b/src/installer.ts
@@ -7,7 +7,7 @@ import {chmodSync} from 'fs';
 import {readdir} from 'fs/promises';
 import path from 'path';
 import semver from 'semver';
-import {IS_LINUX, IS_WINDOWS, IS_MAC} from './utils';
+import {IS_LINUX, IS_WINDOWS} from './utils';
 import {QualityOptions} from './setup-dotnet';
 
 export interface DotnetVersion {
@@ -208,10 +208,12 @@ export class DotnetCoreInstaller {
         scriptArguments.push(`-ProxyBypassList ${process.env['no_proxy']}`);
       }
 
-      scriptArguments.push(
-        '-InstallDir',
-        `'${DotnetCoreInstaller.installationDirectoryWindows}'`
-      );
+      if (!process.env['DOTNET_INSTALL_DIR']) {
+        scriptArguments.push(
+          '-InstallDir',
+          `'${DotnetCoreInstaller.installationDirectoryWindows}'`
+        );
+      }
       // process.env must be explicitly passed in for DOTNET_INSTALL_DIR to be used
       scriptPath =
         (await io.which('pwsh', false)) || (await io.which('powershell', true));
@@ -229,17 +231,12 @@ export class DotnetCoreInstaller {
         this.setQuality(dotnetVersion, scriptArguments);
       }
 
-      if (IS_LINUX) {
+      if (!process.env['DOTNET_INSTALL_DIR']) {
         scriptArguments.push(
           '--install-dir',
-          DotnetCoreInstaller.installationDirectoryLinux
-        );
-      }
-
-      if (IS_MAC) {
-        scriptArguments.push(
-          '--install-dir',
-          DotnetCoreInstaller.installationDirectoryMac
+          IS_LINUX
+            ? DotnetCoreInstaller.installationDirectoryLinux
+            : DotnetCoreInstaller.installationDirectoryMac
         );
       }
     }
@@ -254,7 +251,9 @@ export class DotnetCoreInstaller {
 
     return this.outputDotnetVersion(
       dotnetVersion.value,
-      scriptArguments[scriptArguments.length - 1]
+      process.env['DOTNET_INSTALL_DIR']
+        ? process.env['DOTNET_INSTALL_DIR']
+        : scriptArguments[scriptArguments.length - 1]
     );
   }
 
diff --git a/src/utils.ts b/src/utils.ts
index ff20ee3..77886ce 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,3 +1,2 @@
 export const IS_WINDOWS = process.platform === 'win32';
 export const IS_LINUX = process.platform === 'linux';
-export const IS_MAC = process.platform === 'darwin';