diff --git a/src/vs/workbench/services/themes/browser/fileIconThemeStore.ts b/src/vs/workbench/services/themes/browser/fileIconThemeStore.ts
index 0afad15ee6c..213986a9839 100644
--- a/src/vs/workbench/services/themes/browser/fileIconThemeStore.ts
+++ b/src/vs/workbench/services/themes/browser/fileIconThemeStore.ts
@@ -74,9 +74,10 @@ export class FileIconThemeStore extends Disposable {
 					extensionId: ext.description.identifier.value,
 					extensionPublisher: ext.description.publisher,
 					extensionName: ext.description.name,
-					extensionIsBuiltin: ext.description.isBuiltin
+					extensionIsBuiltin: ext.description.isBuiltin,
+					extensionLocation: ext.description.extensionLocation
 				};
-				this.onIconThemes(ext.description.extensionLocation, extensionData, ext.value, ext.collector);
+				this.onIconThemes(extensionData, ext.value, ext.collector);
 			}
 			for (const theme of this.knownIconThemes) {
 				if (!previousIds[theme.id]) {
@@ -87,7 +88,7 @@ export class FileIconThemeStore extends Disposable {
 		});
 	}
 
-	private onIconThemes(extensionLocation: URI, extensionData: ExtensionData, iconThemes: IThemeExtensionPoint[], collector: ExtensionMessageCollector): void {
+	private onIconThemes(extensionData: ExtensionData, iconThemes: IThemeExtensionPoint[], collector: ExtensionMessageCollector): void {
 		if (!Array.isArray(iconThemes)) {
 			collector.error(nls.localize(
 				'reqarray',
@@ -116,9 +117,9 @@ export class FileIconThemeStore extends Disposable {
 				return;
 			}
 
-			const iconThemeLocation = resources.joinPath(extensionLocation, iconTheme.path);
-			if (!resources.isEqualOrParent(iconThemeLocation, extensionLocation)) {
-				collector.warn(nls.localize('invalid.path.1', "Expected `contributes.{0}.path` ({1}) to be included inside extension's folder ({2}). This might make the extension non-portable.", iconThemeExtPoint.name, iconThemeLocation.path, extensionLocation.path));
+			const iconThemeLocation = resources.joinPath(extensionData.extensionLocation, iconTheme.path);
+			if (!resources.isEqualOrParent(iconThemeLocation, extensionData.extensionLocation)) {
+				collector.warn(nls.localize('invalid.path.1', "Expected `contributes.{0}.path` ({1}) to be included inside extension's folder ({2}). This might make the extension non-portable.", iconThemeExtPoint.name, iconThemeLocation.path, extensionData.extensionLocation.path));
 			}
 
 			let themeData = FileIconThemeData.fromExtensionTheme(iconTheme, iconThemeLocation, extensionData);
@@ -145,10 +146,10 @@ export class FileIconThemeStore extends Disposable {
 		});
 	}
 
-	public findThemeDataByParentLocation(parentLocation: URI | undefined): Promise<FileIconThemeData[]> {
-		if (parentLocation) {
+	public findThemeDataByExtensionLocation(extLocation: URI | undefined): Promise<FileIconThemeData[]> {
+		if (extLocation) {
 			return this.getFileIconThemes().then(allThemes => {
-				return allThemes.filter(t => t.location && resources.isEqualOrParent(t.location, parentLocation));
+				return allThemes.filter(t => t.extensionData && resources.isEqualOrParent(t.extensionData.extensionLocation, extLocation));
 			});
 		}
 		return Promise.resolve([]);
diff --git a/src/vs/workbench/services/themes/browser/workbenchThemeService.ts b/src/vs/workbench/services/themes/browser/workbenchThemeService.ts
index a3b675c68cc..c2d10bf8442 100644
--- a/src/vs/workbench/services/themes/browser/workbenchThemeService.ts
+++ b/src/vs/workbench/services/themes/browser/workbenchThemeService.ts
@@ -285,8 +285,8 @@ export class WorkbenchThemeService implements IWorkbenchThemeService {
 		const extDevLocs = this.environmentService.extensionDevelopmentLocationURI;
 
 		const initializeColorTheme = async () => {
-			if (extDevLocs && extDevLocs.length > 0) { // in dev mode, switch to a theme provided by the extension under dev.
-				const devThemes = await this.colorThemeStore.findThemeDataByParentLocation(extDevLocs[0]);
+			if (extDevLocs && extDevLocs.length === 1) { // in dev mode, switch to a theme provided by the extension under dev.
+				const devThemes = await this.colorThemeStore.findThemeDataByExtensionLocation(extDevLocs[0]);
 				if (devThemes.length) {
 					return this.setColorTheme(devThemes[0].id, ConfigurationTarget.MEMORY);
 				}
@@ -302,8 +302,8 @@ export class WorkbenchThemeService implements IWorkbenchThemeService {
 		};
 
 		const initializeIconTheme = async () => {
-			if (extDevLocs && extDevLocs.length > 0) { // in dev mode, switch to a theme provided by the extension under dev.
-				const devThemes = await this.iconThemeStore.findThemeDataByParentLocation(extDevLocs[0]);
+			if (extDevLocs && extDevLocs.length === 1) { // in dev mode, switch to a theme provided by the extension under dev.
+				const devThemes = await this.iconThemeStore.findThemeDataByExtensionLocation(extDevLocs[0]);
 				if (devThemes.length) {
 					return this.setFileIconTheme(devThemes[0].id, ConfigurationTarget.MEMORY);
 				}
diff --git a/src/vs/workbench/services/themes/common/colorThemeStore.ts b/src/vs/workbench/services/themes/common/colorThemeStore.ts
index 7253ada3afd..32dc2ad1d2f 100644
--- a/src/vs/workbench/services/themes/common/colorThemeStore.ts
+++ b/src/vs/workbench/services/themes/common/colorThemeStore.ts
@@ -71,13 +71,14 @@ export class ColorThemeStore {
 			}
 			this.extensionsColorThemes.length = 0;
 			for (let ext of extensions) {
-				let extensionData = {
+				let extensionData: ExtensionData = {
 					extensionId: ext.description.identifier.value,
 					extensionPublisher: ext.description.publisher,
 					extensionName: ext.description.name,
-					extensionIsBuiltin: ext.description.isBuiltin
+					extensionIsBuiltin: ext.description.isBuiltin,
+					extensionLocation: ext.description.extensionLocation
 				};
-				this.onThemes(ext.description.extensionLocation, extensionData, ext.value, ext.collector);
+				this.onThemes(extensionData, ext.value, ext.collector);
 			}
 			for (const theme of this.extensionsColorThemes) {
 				if (!previousIds[theme.id]) {
@@ -88,7 +89,7 @@ export class ColorThemeStore {
 		});
 	}
 
-	private onThemes(extensionLocation: URI, extensionData: ExtensionData, themes: IThemeExtensionPoint[], collector: ExtensionMessageCollector): void {
+	private onThemes(extensionData: ExtensionData, themes: IThemeExtensionPoint[], collector: ExtensionMessageCollector): void {
 		if (!Array.isArray(themes)) {
 			collector.error(nls.localize(
 				'reqarray',
@@ -108,9 +109,9 @@ export class ColorThemeStore {
 				return;
 			}
 
-			const colorThemeLocation = resources.joinPath(extensionLocation, theme.path);
-			if (!resources.isEqualOrParent(colorThemeLocation, extensionLocation)) {
-				collector.warn(nls.localize('invalid.path.1', "Expected `contributes.{0}.path` ({1}) to be included inside extension's folder ({2}). This might make the extension non-portable.", themesExtPoint.name, colorThemeLocation.path, extensionLocation.path));
+			const colorThemeLocation = resources.joinPath(extensionData.extensionLocation, theme.path);
+			if (!resources.isEqualOrParent(colorThemeLocation, extensionData.extensionLocation)) {
+				collector.warn(nls.localize('invalid.path.1', "Expected `contributes.{0}.path` ({1}) to be included inside extension's folder ({2}). This might make the extension non-portable.", themesExtPoint.name, colorThemeLocation.path, extensionData.extensionLocation.path));
 			}
 
 			let themeData = ColorThemeData.fromExtensionTheme(theme, colorThemeLocation, extensionData);
@@ -148,10 +149,10 @@ export class ColorThemeStore {
 		});
 	}
 
-	public findThemeDataByParentLocation(parentLocation: URI | undefined): Promise<ColorThemeData[]> {
-		if (parentLocation) {
+	public findThemeDataByExtensionLocation(extLocation: URI | undefined): Promise<ColorThemeData[]> {
+		if (extLocation) {
 			return this.getColorThemes().then(allThemes => {
-				return allThemes.filter(t => t.location && resources.isEqualOrParent(t.location, parentLocation));
+				return allThemes.filter(t => t.extensionData && resources.isEqual(t.extensionData.extensionLocation, extLocation));
 			});
 		}
 		return Promise.resolve([]);
diff --git a/src/vs/workbench/services/themes/common/workbenchThemeService.ts b/src/vs/workbench/services/themes/common/workbenchThemeService.ts
index 4756204b595..16765a13851 100644
--- a/src/vs/workbench/services/themes/common/workbenchThemeService.ts
+++ b/src/vs/workbench/services/themes/common/workbenchThemeService.ts
@@ -8,6 +8,7 @@ import { Event } from 'vs/base/common/event';
 import { Color } from 'vs/base/common/color';
 import { ITheme, IThemeService, IIconTheme } from 'vs/platform/theme/common/themeService';
 import { ConfigurationTarget } from 'vs/platform/configuration/common/configuration';
+import { URI } from 'vs/base/common/uri';
 
 export const IWorkbenchThemeService = createDecorator<IWorkbenchThemeService>('themeService');
 
@@ -101,6 +102,7 @@ export interface ExtensionData {
 	extensionPublisher: string;
 	extensionName: string;
 	extensionIsBuiltin: boolean;
+	extensionLocation: URI;
 }
 
 export interface IThemeExtensionPoint {