diff --git a/src/vs/workbench/api/electron-browser/mainThreadDebugService.ts b/src/vs/workbench/api/electron-browser/mainThreadDebugService.ts
index aed656accd0..c7a0ba78a06 100644
--- a/src/vs/workbench/api/electron-browser/mainThreadDebugService.ts
+++ b/src/vs/workbench/api/electron-browser/mainThreadDebugService.ts
@@ -177,8 +177,8 @@ export class MainThreadDebugService implements MainThreadDebugServiceShape {
 	}
 
 	public $startDebugging(_folderUri: uri | undefined, nameOrConfiguration: string | IConfig): TPromise<boolean> {
-		const folderUriString = _folderUri ? uri.revive(_folderUri).toString() : undefined;
-		const launch = folderUriString ? this.debugService.getConfigurationManager().getLaunches().filter(l => l.workspace && l.workspace.uri.toString() === folderUriString).pop() : undefined;
+		const folderUri = _folderUri ? uri.revive(_folderUri) : undefined;
+		const launch = this.debugService.getConfigurationManager().getLaunch(folderUri);
 		return this.debugService.startDebugging(launch, nameOrConfiguration).then(x => {
 			return true;
 		}, err => {
diff --git a/src/vs/workbench/parts/debug/browser/debugActionItems.ts b/src/vs/workbench/parts/debug/browser/debugActionItems.ts
index 4d6367248ac..14ab35e5986 100644
--- a/src/vs/workbench/parts/debug/browser/debugActionItems.ts
+++ b/src/vs/workbench/parts/debug/browser/debugActionItems.ts
@@ -156,7 +156,7 @@ export class StartDebugActionItem implements IActionItem {
 		const manager = this.debugService.getConfigurationManager();
 		const launches = manager.getLaunches();
 		const inWorkspace = this.contextService.getWorkbenchState() === WorkbenchState.WORKSPACE;
-		manager.getLaunches().forEach(launch =>
+		launches.forEach(launch =>
 			launch.getConfigurationNames().forEach(name => {
 				if (name === manager.selectedConfiguration.name && launch === manager.selectedConfiguration.launch) {
 					this.selected = this.options.length;
diff --git a/src/vs/workbench/parts/debug/common/debug.ts b/src/vs/workbench/parts/debug/common/debug.ts
index 164cad54b53..7ba05b9040d 100644
--- a/src/vs/workbench/parts/debug/common/debug.ts
+++ b/src/vs/workbench/parts/debug/common/debug.ts
@@ -429,6 +429,8 @@ export interface IConfigurationManager {
 
 	getLaunches(): ILaunch[];
 
+	getLaunch(workspaceUri: uri): ILaunch | undefined;
+
 	/**
 	 * Allows to register on change of selected debug configuration.
 	 */
diff --git a/src/vs/workbench/parts/debug/electron-browser/debugConfigurationManager.ts b/src/vs/workbench/parts/debug/electron-browser/debugConfigurationManager.ts
index adcdcc16cf2..ec04698d860 100644
--- a/src/vs/workbench/parts/debug/electron-browser/debugConfigurationManager.ts
+++ b/src/vs/workbench/parts/debug/electron-browser/debugConfigurationManager.ts
@@ -390,6 +390,14 @@ export class ConfigurationManager implements IConfigurationManager {
 		return this.launches;
 	}
 
+	public getLaunch(workspaceUri: uri): ILaunch {
+		if (!uri.isUri(workspaceUri)) {
+			return undefined;
+		}
+
+		return this.launches.filter(l => l.workspace && l.workspace.uri.toString() === workspaceUri.toString()).pop();
+	}
+
 	public get selectedConfiguration(): { launch: ILaunch, name: string } {
 		return {
 			launch: this.selectedLaunch,
diff --git a/src/vs/workbench/parts/debug/electron-browser/debugService.ts b/src/vs/workbench/parts/debug/electron-browser/debugService.ts
index 065a0fad315..fc3bd185600 100644
--- a/src/vs/workbench/parts/debug/electron-browser/debugService.ts
+++ b/src/vs/workbench/parts/debug/electron-browser/debugService.ts
@@ -1061,7 +1061,7 @@ export class DebugService implements debug.IDebugService {
 						// Read the configuration again if a launch.json has been changed, if not just use the inmemory configuration
 						let config = process.configuration;
 
-						const launch = this.configurationManager.getLaunches().filter(l => l.workspace && process.session.root && l.workspace.uri.toString() === process.session.root.uri.toString()).pop();
+						const launch = process.session.root ? this.configurationManager.getLaunch(process.session.root.uri) : undefined;
 						if (this.launchJsonChanged && launch) {
 							this.launchJsonChanged = false;
 							config = launch.getConfiguration(process.configuration.name) || config;