diff --git a/src/services/services.ts b/src/services/services.ts
index 42b3ac3b31d..b769ee2da3e 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -1158,7 +1158,7 @@ namespace ts {
         function getValidSourceFile(fileName: string): SourceFile {
             const sourceFile = program.getSourceFile(fileName);
             if (!sourceFile) {
-                throw new Error(`Could not find sourceFile: '${fileName}' in ${program && JSON.stringify(program.getSourceFiles().map(f => f.fileName))}.`);
+                throw new Error(`Could not find sourceFile: '${fileName}'.`);
             }
             return sourceFile;
         }