diff --git a/src/compiler/watch.ts b/src/compiler/watch.ts
index 8a94393e2ce..6206c22eeba 100644
--- a/src/compiler/watch.ts
+++ b/src/compiler/watch.ts
@@ -275,7 +275,7 @@ namespace ts {
         }
     }
 
-    export function setGetSourceFileAsHashVersioned(compilerHost: CompilerHost, host: ProgramHost<any>) {
+    export function setGetSourceFileAsHashVersioned(compilerHost: CompilerHost, host: { createHash?(data: string): string; }) {
         const originalGetSourceFile = compilerHost.getSourceFile;
         const computeHash = host.createHash || generateDjb2Hash;
         compilerHost.getSourceFile = (...args) => {
diff --git a/src/tsc/tsc.ts b/src/tsc/tsc.ts
index 499848fdf92..31b5d7d75d8 100644
--- a/src/tsc/tsc.ts
+++ b/src/tsc/tsc.ts
@@ -263,6 +263,7 @@ namespace ts {
         const host = createCompilerHost(options);
         const currentDirectory = host.getCurrentDirectory();
         const getCanonicalFileName = createGetCanonicalFileName(host.useCaseSensitiveFileNames());
+        setGetSourceFileAsHashVersioned(host, sys);
         changeCompilerHostLikeToUseCache(host, fileName => toPath(fileName, currentDirectory, getCanonicalFileName));
         enableStatistics(options);
         const oldProgram = readBuilderProgram(options, path => host.readFile(path));