diff --git a/src/compiler/sys.ts b/src/compiler/sys.ts
index 585fb60df32a6..13bbfc2ab153f 100644
--- a/src/compiler/sys.ts
+++ b/src/compiler/sys.ts
@@ -34,6 +34,8 @@ namespace ts {
         realpath?(path: string): string;
         /*@internal*/ getEnvironmentVariable(name: string): string;
         /*@internal*/ tryEnableSourceMapsForHost?(): void;
+        setTimeout?(callback: (...args: any[]) => void, ms: number, ...args: any[]): any;
+        clearTimeout?(timeoutId: any): void;
     }
 
     export interface FileWatcher {
@@ -560,7 +562,9 @@ namespace ts {
                     catch (e) {
                         // Could not enable source maps.
                     }
-                }
+                },
+                setTimeout,
+                clearTimeout
             };
             return nodeSystem;
         }
diff --git a/src/compiler/tsc.ts b/src/compiler/tsc.ts
index aa277c9b5070d..10d4a0c1d3679 100644
--- a/src/compiler/tsc.ts
+++ b/src/compiler/tsc.ts
@@ -250,8 +250,8 @@ namespace ts {
         let compilerOptions: CompilerOptions;                       // Compiler options for compilation
         let compilerHost: CompilerHost;                             // Compiler host
         let hostGetSourceFile: typeof compilerHost.getSourceFile;   // getSourceFile method from default host
-        let timerHandleForRecompilation: number;                    // Handle for 0.25s wait timer to trigger recompilation
-        let timerHandleForDirectoryChanges: number;                 // Handle for 0.25s wait timer to trigger directory change handler
+        let timerHandleForRecompilation: any;                    // Handle for 0.25s wait timer to trigger recompilation
+        let timerHandleForDirectoryChanges: any;                 // Handle for 0.25s wait timer to trigger directory change handler
 
         // This map stores and reuses results of fileExists check that happen inside 'createProgram'
         // This allows to save time in module resolution heavy scenarios when existence of the same file might be checked multiple times.
@@ -503,10 +503,14 @@ namespace ts {
         }
 
         function startTimerForHandlingDirectoryChanges() {
+            if (!sys.setTimeout || !sys.clearTimeout) {
+                return;
+            }
+
             if (timerHandleForDirectoryChanges) {
-                clearTimeout(timerHandleForDirectoryChanges);
+                sys.clearTimeout(timerHandleForDirectoryChanges);
             }
-            timerHandleForDirectoryChanges = setTimeout(directoryChangeHandler, 250);
+            timerHandleForDirectoryChanges = sys.setTimeout(directoryChangeHandler, 250);
         }
 
         function directoryChangeHandler() {
@@ -525,10 +529,14 @@ namespace ts {
         // operations (such as saving all modified files in an editor) a chance to complete before we kick
         // off a new compilation.
         function startTimerForRecompilation() {
+            if (!sys.setTimeout || !sys.clearTimeout) {
+                return;
+            }
+
             if (timerHandleForRecompilation) {
-                clearTimeout(timerHandleForRecompilation);
+                sys.clearTimeout(timerHandleForRecompilation);
             }
-            timerHandleForRecompilation = setTimeout(recompile, 250);
+            timerHandleForRecompilation = sys.setTimeout(recompile, 250);
         }
 
         function recompile() {