diff --git a/src/vs/workbench/api/common/extHostTypes.ts b/src/vs/workbench/api/common/extHostTypes.ts
index 5e103f86870..6c54d1f4f9f 100644
--- a/src/vs/workbench/api/common/extHostTypes.ts
+++ b/src/vs/workbench/api/common/extHostTypes.ts
@@ -2189,11 +2189,16 @@ export enum ConfigurationTarget {
 @es5ClassCompat
 export class RelativePattern implements IRelativePattern {
 	base: string;
-	baseFolder?: URI;
-
 	pattern: string;
 
-	constructor(base: URI | vscode.WorkspaceFolder | string, pattern: string) {
+	// expose a `baseFolder: URI` property as a workaround for the short-coming
+	// of `IRelativePattern` only supporting `base: string` which always translates
+	// to a `file://` URI. With `baseFolder` we can support non-file based folders
+	// in searches
+	// (https://github.com/microsoft/vscode/commit/6326543b11cf4998c8fd1564cab5c429a2416db3)
+	readonly baseFolder?: URI;
+
+	constructor(base: vscode.WorkspaceFolder | URI | string, pattern: string) {
 		if (typeof base !== 'string') {
 			if (!base || !URI.isUri(base) && !URI.isUri(base.uri)) {
 				throw illegalArgument('base');
@@ -2205,6 +2210,7 @@ export class RelativePattern implements IRelativePattern {
 		}
 
 		if (typeof base === 'string') {
+			this.baseFolder = URI.file(base);
 			this.base = base;
 		} else if (URI.isUri(base)) {
 			this.baseFolder = base;
diff --git a/src/vs/workbench/api/common/extHostWorkspace.ts b/src/vs/workbench/api/common/extHostWorkspace.ts
index 1434932e36e..3e0de07e3f4 100644
--- a/src/vs/workbench/api/common/extHostWorkspace.ts
+++ b/src/vs/workbench/api/common/extHostWorkspace.ts
@@ -467,17 +467,7 @@ export class ExtHostWorkspace implements ExtHostWorkspaceShape, IExtHostWorkspac
 			} :
 			options.previewOptions;
 
-		let includePattern: string | undefined;
-		let folder: URI | undefined;
-		if (options.include) {
-			if (typeof options.include === 'string') {
-				includePattern = options.include;
-			} else {
-				includePattern = options.include.pattern;
-				folder = (options.include as RelativePattern).baseFolder || URI.file(options.include.base);
-			}
-		}
-
+		const { includePattern, folder } = parseSearchInclude(options.include);
 		const excludePattern = (typeof options.exclude === 'string') ? options.exclude :
 			options.exclude ? options.exclude.pattern : undefined;
 		const queryOptions: ITextQueryBuilderOptions = {
@@ -572,14 +562,12 @@ function parseSearchInclude(include: RelativePattern | string | undefined): { in
 			includePattern = include;
 		} else {
 			includePattern = include.pattern;
-
-			// include.base must be an absolute path
 			includeFolder = include.baseFolder || URI.file(include.base);
 		}
 	}
 
 	return {
-		includePattern: includePattern,
+		includePattern,
 		folder: includeFolder
 	};
 }