diff --git a/src/harness/compilerRunner.ts b/src/harness/compilerRunner.ts
index 7045a1196d0..4ca33f92804 100644
--- a/src/harness/compilerRunner.ts
+++ b/src/harness/compilerRunner.ts
@@ -10,7 +10,7 @@ const enum CompilerTestType {
 }
 
 class CompilerBaselineRunner extends RunnerBase {
-    private basePath = 'tests/cases';
+    protected basePath = 'tests/cases';
     private errors: boolean;
     private emit: boolean;
     private decl: boolean;
@@ -113,10 +113,7 @@ class CompilerBaselineRunner extends RunnerBase {
                 for (var i = 0; i < tcSettings.length; ++i) {
                     // noImplicitAny is passed to getCompiler, but target is just passed in the settings blob to setCompilerSettings
                     if (!createNewInstance && (tcSettings[i].flag == "noimplicitany" || tcSettings[i].flag === 'target')) {
-                        harnessCompiler = Harness.Compiler.getCompiler({
-                            useExistingInstance: false,
-                            optionsForFreshInstance: { useMinimalDefaultLib: true, noImplicitAny: tcSettings[i].flag === "noimplicitany" }
-                        });
+                        harnessCompiler = Harness.Compiler.getCompiler();
                         harnessCompiler.setCompilerSettings(tcSettings);
                         createNewInstance = true;
                     }
@@ -125,10 +122,7 @@ class CompilerBaselineRunner extends RunnerBase {
 
             afterEach(() => {
                 if (createNewInstance) {
-                    harnessCompiler = Harness.Compiler.getCompiler({
-                        useExistingInstance: false,
-                        optionsForFreshInstance: { useMinimalDefaultLib: true, noImplicitAny: false }
-                    });
+                    harnessCompiler = Harness.Compiler.getCompiler();
                     createNewInstance = false;
                 }
             });
@@ -312,10 +306,7 @@ class CompilerBaselineRunner extends RunnerBase {
 
     public initializeTests() {
         describe("Setup compiler for compiler baselines", () => {
-            var harnessCompiler = Harness.Compiler.getCompiler({
-                useExistingInstance: false,
-                optionsForFreshInstance: { useMinimalDefaultLib: true, noImplicitAny: false }
-            });
+            var harnessCompiler = Harness.Compiler.getCompiler();
             this.parseOptions();
         });
 
@@ -332,10 +323,7 @@ class CompilerBaselineRunner extends RunnerBase {
         }
 
         describe("Cleanup after compiler baselines", () => {
-            var harnessCompiler = Harness.Compiler.getCompiler({
-                useExistingInstance: false,
-                optionsForFreshInstance: { useMinimalDefaultLib: true, noImplicitAny: false }
-            });
+            var harnessCompiler = Harness.Compiler.getCompiler();
         });
     }
 
diff --git a/src/harness/fourslashRunner.ts b/src/harness/fourslashRunner.ts
index b7e59437456..1ecb02df292 100644
--- a/src/harness/fourslashRunner.ts
+++ b/src/harness/fourslashRunner.ts
@@ -15,10 +15,6 @@ class FourslashRunner extends RunnerBase {
         }
 
         describe("fourslash tests", () => {
-            before(() => {
-                Harness.Compiler.getCompiler({ useExistingInstance: false });
-            });
-
             this.tests.forEach((fn: string) => {
                 fn = ts.normalizeSlashes(fn);
                 var justName = fn.replace(/^.*[\\\/]/, '');
@@ -33,10 +29,6 @@ class FourslashRunner extends RunnerBase {
                     });
                 }
             });
-
-            after(() => {
-                Harness.Compiler.getCompiler({ useExistingInstance: false });
-            });
         });
 
         describe('Generate Tao XML', () => {
diff --git a/src/harness/harness.ts b/src/harness/harness.ts
index f9c20a1893a..3bc635e2ab4 100644
--- a/src/harness/harness.ts
+++ b/src/harness/harness.ts
@@ -1029,7 +1029,7 @@ module Harness {
         /** Returns the singleton harness compiler instance for generating and running tests.
             If required a fresh compiler instance will be created, otherwise the existing singleton will be re-used.
         */
-        export function getCompiler(opts?: { useExistingInstance: boolean; optionsForFreshInstance?: { useMinimalDefaultLib: boolean; noImplicitAny: boolean; } }) {
+        export function getCompiler() {
             return harnessCompiler = harnessCompiler || new HarnessCompiler();
         }