diff --git a/src/command.ts b/src/command.ts
index e11e641..c005819 100644
--- a/src/command.ts
+++ b/src/command.ts
@@ -1,7 +1,7 @@
 'use strict';
 
 import * as path from 'path';
-import { exec, ExecOptions } from 'child_process';
+import { exec, execSync, ExecOptionsWithStringEncoding } from 'child_process';
 import * as constants from './constants';
 import * as utils from './utils';
 
@@ -21,26 +21,42 @@ export class Command {
         this.rcPath = path.join(rootPath, `${constants.direnv.rc}`);
     }
     // Private methods
-    private exec(options: CommandExecOptions): Thenable<string> {
+    private execAsync(options: CommandExecOptions): Thenable<string> {
+        return <Thenable<string>>this.exec(false, options)
+    }
+
+    private execSync(options: CommandExecOptions): string {
+        return <string>this.exec(true, options)
+    }
+
+    private exec(sync: boolean, options: CommandExecOptions): Thenable<string> | string {
         let direnvCmd = [constants.direnv.cmd, options.cmd].join(' ');
-        let execOptions: ExecOptions = {};
+        let execOptions: ExecOptionsWithStringEncoding = { encoding: 'utf8' };
         if (options.cwd == null || options.cwd) {
             execOptions.cwd = this.rootPath;
         }
-        return new Promise((resolve, reject) => {
-            exec(direnvCmd, execOptions, (err, stdout, stderr) => {
-                if (err) {
-                    err.message = stderr;
-                    reject(err);
-                } else {
-                    resolve(stdout);
-                }
+        if (sync) {
+            console.log("NOTE: executing command synchronously", direnvCmd)
+            return execSync(direnvCmd, execOptions);
+        } else {
+            return new Promise((resolve, reject) => {
+                exec(direnvCmd, execOptions, (err, stdout, stderr) => {
+                    if (err) {
+                        err.message = stderr;
+                        reject(err);
+                    } else {
+                        resolve(stdout);
+                    }
+                });
             });
-        });
+        }
     }
     // Public methods
-    version = () => this.exec({ cmd: 'version' });
-    allow = () => this.exec({ cmd: 'allow' });
-    deny = () => this.exec({ cmd: 'deny' });
-    exportJSON = () => this.exec({ cmd: 'export json' }).then((o) => o ? JSON.parse(o) : {});
+    version = () => this.execAsync({ cmd: 'version' });
+    allow = () => this.execAsync({ cmd: 'allow' });
+    deny = () => this.execAsync({ cmd: 'deny' });
+    exportJSONSync = () => {
+        const o = this.execSync({ cmd: 'export json' })
+        return o ? JSON.parse(o) : {}
+    };
 }
diff --git a/src/main.ts b/src/main.ts
index d4db4aa..45b4560 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -5,7 +5,7 @@ import * as utils from './utils';
 import * as constants from './constants';
 import { Command } from './command';
 
-let oldEnvDiff = {};
+let restartExtensionHost= () => vscode.commands.executeCommand("workbench.action.restartExtensionHost")
 let command = new Command(vscode.workspace.rootPath);
 let watcher = vscode.workspace.createFileSystemWatcher(command.rcPath, true);
 let displayError = (e) =>
@@ -15,40 +15,55 @@ let version = () =>
     command.version().then(v => vscode.window.showInformationMessage(constants.messages.version(v)), displayError);
 let revertFromOption = (option) => {
     if (option === constants.vscode.extension.actions.revert) {
-        utils.assign(process.env, oldEnvDiff);
-        oldEnvDiff = {};
-        vscode.window.showInformationMessage(constants.messages.reverted);
+        restartExtensionHost()
     }
 };
-let assignEnvDiff = (options: { showSuccess: boolean }) => {
-    return command.exportJSON().then((envDiff) => {
-        Object.keys(envDiff).forEach((key) => {
-            if (key.indexOf('DIRENV_') === -1 && oldEnvDiff[key] !== envDiff[key]) {
-                oldEnvDiff[key] = process.env[key];
-            }
-        });
-        return utils.assign(process.env, envDiff);
-    }).then(() => {
+
+let initialize: () => Thenable<number> = () => {
+    try {
+        const envDiff = command.exportJSONSync()
+        console.log("loaded direnv diff:", envDiff)
+        return Promise.resolve(utils.assign(process.env, envDiff))
+    } catch(err) {
+        return Promise.reject<number>(err)
+    }
+}
+
+let postInitialize = (result: Thenable<number>, options: { showSuccess: boolean }) => {
+    return result.then(() => {
         if (options.showSuccess) {
             return vscode.window.showInformationMessage(constants.messages.assign.success);
         }
     }, (err) => {
         if (err.message.indexOf(`${constants.direnv.rc} is blocked`) !== -1) {
             return vscode.window.showWarningMessage(constants.messages.assign.warn,
-                constants.vscode.extension.actions.allow, constants.vscode.extension.actions.view);
+                constants.vscode.extension.actions.allow, constants.vscode.extension.actions.view
+            ).then((option) => {
+                if (option === constants.vscode.extension.actions.allow) {
+                    return allow();
+                } else if (option === constants.vscode.extension.actions.view) {
+                    return viewThenAllow();
+                }
+            });
         } else {
             return displayError(err);
         }
-    }).then((option) => {
-        if (option === constants.vscode.extension.actions.allow) {
-            return allow();
-        } else if (option === constants.vscode.extension.actions.view) {
-            return viewThenAllow();
+    })
+}
+
+let reinitialize = (options: { showSuccess: boolean }) => {
+    const result = initialize()
+    result.then((changes) => {
+        if (changes > 0) {
+            postInitialize(result, options).then(() => restartExtensionHost())
+        } else {
+            return postInitialize(result, options)
         }
-    });
+    })
 };
+
 let allow = () => {
-    return command.allow().then(() => assignEnvDiff({ showSuccess: true }), (err) => {
+    return command.allow().then(() => reinitialize({ showSuccess: true }), (err) => {
         if (err.message.indexOf(`${constants.direnv.rc} file not found`) !== -1) {
             return vscode.commands.executeCommand(constants.vscode.commands.open, vscode.Uri.file(command.rcPath));
         } else {
@@ -72,11 +87,15 @@ watcher.onDidChange((e) => vscode.window.showWarningMessage(constants.messages.r
 watcher.onDidDelete((e) => vscode.window.showWarningMessage(constants.messages.rc.deleted,
     constants.vscode.extension.actions.revert).then(revertFromOption));
 
+// NOTE: we apply synchronously on extension import to ensure it takes effect for all extensions.
+// This means plugin activation state isn't actually respected.
+let initializeResult = initialize()
+
 export function activate(context: vscode.ExtensionContext) {
     context.subscriptions.push(vscode.commands.registerCommand('direnv.version', version));
     context.subscriptions.push(vscode.commands.registerCommand('direnv.view', view));
     context.subscriptions.push(vscode.commands.registerCommand('direnv.allow', allow));
-    assignEnvDiff({ showSuccess: false });
+    postInitialize(initializeResult, { showSuccess: false })
 }
 
 export function deactivate() {
diff --git a/src/utils.ts b/src/utils.ts
index 2aec007..9d448d9 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,6 +1,16 @@
 'use strict';
 
-export function assign(destination: any, ...sources: any[]): any {
-    sources.forEach(source => Object.keys(source).forEach((key) => destination[key] = source[key]));
-    return destination;
+export function assign(destination: any, ...sources: any[]): number {
+    let changes = 0
+    sources.forEach(source => Object.keys(source).forEach((key) => {
+        if (source[key] != destination[key]) {
+            changes += 1
+            if (source[key] == null) {
+                delete destination[key]
+            } else {
+                destination[key] = source[key]
+            }
+        }
+    }));
+    return changes
 }