diff --git a/src/services/findAllReferences.ts b/src/services/findAllReferences.ts
index 6bc55f54ff7..1830be27053 100644
--- a/src/services/findAllReferences.ts
+++ b/src/services/findAllReferences.ts
@@ -234,7 +234,8 @@ namespace ts.FindAllReferences.Core {
     export function getReferencedSymbolsForNode(position: number, node: Node, program: Program, sourceFiles: ReadonlyArray<SourceFile>, cancellationToken: CancellationToken, options: Options = {}, sourceFilesSet: ReadonlyMap<true> = arrayToSet(sourceFiles, f => f.fileName)): SymbolAndEntries[] | undefined {
         if (isSourceFile(node)) {
             const reference = GoToDefinition.getReferenceAtPosition(node, position, program);
-            return reference && getReferencedSymbolsForModule(program, program.getTypeChecker().getMergedSymbol(reference.file.symbol), /*excludeImportTypeOfExportEquals*/ false, sourceFiles, sourceFilesSet);
+            const moduleSymbol = reference && program.getTypeChecker().getMergedSymbol(reference.file.symbol);
+            return moduleSymbol && getReferencedSymbolsForModule(program, moduleSymbol, /*excludeImportTypeOfExportEquals*/ false, sourceFiles, sourceFilesSet);
         }
 
         if (!options.implementations) {
diff --git a/src/services/services.ts b/src/services/services.ts
index cc195740aef..6ab839c3cce 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -1537,7 +1537,8 @@ namespace ts {
         }
 
         function getDocumentHighlights(fileName: string, position: number, filesToSearch: ReadonlyArray<string>): DocumentHighlights[] | undefined {
-            Debug.assert(filesToSearch.some(f => normalizePath(f) === fileName));
+            const normalizedFileName = normalizePath(fileName);
+            Debug.assert(filesToSearch.some(f => normalizePath(f) === normalizedFileName));
             synchronizeHostData();
             const sourceFilesToSearch = map(filesToSearch, f => Debug.assertDefined(program.getSourceFile(f)));
             const sourceFile = getValidSourceFile(fileName);