diff --git a/src/goImplementations.ts b/src/goImplementations.ts
index 82f5a16bd..e847700a0 100644
--- a/src/goImplementations.ts
+++ b/src/goImplementations.ts
@@ -28,13 +28,23 @@ interface GuruImplementsOutput {
 
 export class GoImplementationProvider implements vscode.ImplementationProvider {
 	public provideImplementation(document: vscode.TextDocument, position: vscode.Position, token: vscode.CancellationToken): Thenable<vscode.Definition> {
+		// To keep `guru implements` fast we want to restrict the scope of the search to current workpsace
+		// If no workpsace is open, then no-op
+		let root = vscode.workspace.rootPath;
+		if (vscode.workspace.getWorkspaceFolder(document.uri)) {
+			root = vscode.workspace.getWorkspaceFolder(document.uri).uri.fsPath;
+		}
+		if (!root) {
+			vscode.window.showInformationMessage('Cannot find implementations when there is no workspace open.');
+			return;
+		}
+
 		return new Promise<vscode.Definition>((resolve, reject) => {
 			if (token.isCancellationRequested) {
 				return resolve(null);
 			}
 			let env = getToolsEnvVars();
-			let cwd = vscode.workspace.getWorkspaceFolder(document.uri).uri.fsPath;
-			let listProcess = cp.execFile(getGoRuntimePath(), ['list', '-e', '-json'], { cwd, env }, (err, stdout, stderr) => {
+			let listProcess = cp.execFile(getGoRuntimePath(), ['list', '-e', '-json'], { cwd: root, env }, (err, stdout, stderr) => {
 				if (err) {
 					return reject(err);
 				}
@@ -47,7 +57,7 @@ export class GoImplementationProvider implements vscode.ImplementationProvider {
 				let buildTags = '"' + vscode.workspace.getConfiguration('go', document.uri)['buildTags'] + '"';
 				let args = ['-scope', `${scope}/...`, '-json', '-tags', buildTags, 'implements', `${filename}:#${offset.toString()}`];
 
-				let guruProcess = cp.execFile(goGuru, args, {env}, (err, stdout, stderr) => {
+				let guruProcess = cp.execFile(goGuru, args, { env }, (err, stdout, stderr) => {
 					if (err && (<any>err).code === 'ENOENT') {
 						promptForMissingTool('guru');
 						return resolve(null);
diff --git a/src/goMain.ts b/src/goMain.ts
index 587423584..d63a8ffe8 100644
--- a/src/goMain.ts
+++ b/src/goMain.ts
@@ -127,10 +127,13 @@ export function activate(ctx: vscode.ExtensionContext): void {
 		let gopath = getCurrentGoPath();
 
 		let wasInfered = vscode.workspace.getConfiguration('go', vscode.window.activeTextEditor ? vscode.window.activeTextEditor.document.uri : null)['inferGopath'];
-		let root = vscode.window.activeTextEditor ? (vscode.workspace.getWorkspaceFolder(vscode.window.activeTextEditor.document.uri) || vscode.window.activeTextEditor.document).uri.fsPath : vscode.workspace.rootPath;
+		let root = vscode.workspace.rootPath;
+		if (vscode.window.activeTextEditor && vscode.workspace.getWorkspaceFolder(vscode.window.activeTextEditor.document.uri)) {
+			root = vscode.workspace.getWorkspaceFolder(vscode.window.activeTextEditor.document.uri).uri.fsPath;
+		}
 
 		// not only if it was configured, but if it was successful.
-		if (wasInfered && root.indexOf(gopath) === 0) {
+		if (wasInfered && root && root.indexOf(gopath) === 0) {
 			const inferredFrom = vscode.window.activeTextEditor ? 'current folder' : 'workspace root';
 			vscode.window.showInformationMessage(`Current GOPATH is inferred from ${inferredFrom}: ${gopath}`);
 		} else {
diff --git a/src/goPath.ts b/src/goPath.ts
index 30a0197da..302d579db 100644
--- a/src/goPath.ts
+++ b/src/goPath.ts
@@ -148,6 +148,10 @@ export function parseEnvFile(path: string): { [key: string]: string } {
 
 // Walks up given folder path to return the closest ancestor that has `src` as a child
 export function getInferredGopath(folderPath: string): string {
+	if (!folderPath) {
+		return;
+	}
+
 	let dirs = folderPath.toLowerCase().split(path.sep);
 
 	// find src directory closest to given folder path
diff --git a/src/goSignature.ts b/src/goSignature.ts
index 14c5ca942..d20824a2d 100755
--- a/src/goSignature.ts
+++ b/src/goSignature.ts
@@ -19,7 +19,6 @@ export class GoSignatureHelpProvider implements SignatureHelpProvider {
 	}
 
 	public provideSignatureHelp(document: TextDocument, position: Position, token: CancellationToken): Promise<SignatureHelp> {
-		let goConfig = this.goConfig;
 		if (!this.goConfig) {
 			this.goConfig = vscode.workspace.getConfiguration('go', document.uri);
 		}
@@ -30,6 +29,7 @@ export class GoSignatureHelpProvider implements SignatureHelpProvider {
 		}
 		let callerPos = this.previousTokenPosition(document, theCall.openParen);
 		// Temporary fix to fall back to godoc if guru is the set docsTool
+		let goConfig = this.goConfig;
 		if (goConfig['docsTool'] === 'guru') {
 			goConfig = Object.assign({}, goConfig, { 'docsTool': 'godoc' });
 		}
diff --git a/src/goSymbol.ts b/src/goSymbol.ts
index c166f8482..83d746388 100644
--- a/src/goSymbol.ts
+++ b/src/goSymbol.ts
@@ -47,7 +47,14 @@ export class GoWorkspaceSymbolProvider implements vscode.WorkspaceSymbolProvider
 				symbols.push(symbolInfo);
 			});
 		};
-		let root = vscode.window.activeTextEditor ? (vscode.workspace.getWorkspaceFolder(vscode.window.activeTextEditor.document.uri) || vscode.window.activeTextEditor.document).uri.fsPath : vscode.workspace.rootPath;
+		let root = vscode.workspace.rootPath;
+		if (vscode.window.activeTextEditor && vscode.workspace.getWorkspaceFolder(vscode.window.activeTextEditor.document.uri)) {
+			root = vscode.workspace.getWorkspaceFolder(vscode.window.activeTextEditor.document.uri).uri.fsPath;
+		}
+		if (!root) {
+			vscode.window.showInformationMessage('No workspace is open to find symbols.');
+			return;
+		}
 
 		return getWorkspaceSymbols(root, query).then(results => {
 			let symbols: vscode.SymbolInformation[] = [];
diff --git a/src/goTest.ts b/src/goTest.ts
index 2803fc02f..16ec2d1cb 100644
--- a/src/goTest.ts
+++ b/src/goTest.ts
@@ -115,9 +115,17 @@ export function testCurrentPackage(goConfig: vscode.WorkspaceConfiguration, args
  * @param goConfig Configuration for the Go extension.
  */
 export function testWorkspace(goConfig: vscode.WorkspaceConfiguration, args: any) {
+	let dir = vscode.workspace.rootPath;
+	if (vscode.window.activeTextEditor && vscode.workspace.getWorkspaceFolder(vscode.window.activeTextEditor.document.uri)) {
+		dir = vscode.workspace.getWorkspaceFolder(vscode.window.activeTextEditor.document.uri).uri.fsPath;
+	}
+	if (!dir) {
+		vscode.window.showInformationMessage('No workspace is open to run tests.');
+		return;
+	}
 	const testConfig = {
 		goConfig: goConfig,
-		dir: vscode.window.activeTextEditor ? (vscode.workspace.getWorkspaceFolder(vscode.window.activeTextEditor.document.uri) || vscode.window.activeTextEditor.document).uri.fsPath : vscode.workspace.rootPath,
+		dir: dir,
 		flags: getTestFlags(goConfig, args),
 		includeSubDirectories: true
 	};
diff --git a/src/util.ts b/src/util.ts
index 5ab70f4a6..18c386bf1 100644
--- a/src/util.ts
+++ b/src/util.ts
@@ -309,8 +309,8 @@ export function getToolsEnvVars(): any {
 }
 
 export function getCurrentGoPath(workspaceUri?: vscode.Uri): string {
-	if (!workspaceUri && vscode.window.activeTextEditor) {
-		workspaceUri = (vscode.workspace.getWorkspaceFolder(vscode.window.activeTextEditor.document.uri) || vscode.window.activeTextEditor.document).uri;
+	if (!workspaceUri && vscode.window.activeTextEditor && vscode.workspace.getWorkspaceFolder(vscode.window.activeTextEditor.document.uri)) {
+		workspaceUri = vscode.workspace.getWorkspaceFolder(vscode.window.activeTextEditor.document.uri).uri;
 	}
 	const config = vscode.workspace.getConfiguration('go', workspaceUri);
 	const currentRoot = workspaceUri ? workspaceUri.fsPath : vscode.workspace.rootPath;