diff --git a/src/services/services.ts b/src/services/services.ts
index 622c9de7ba3..7f5772d1489 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -1798,7 +1798,7 @@ namespace ts {
             const span = createTextSpanFromBounds(start, end);
             const formatContext = formatting.getFormatContext(formatOptions);
 
-            return flatMap(deduplicate(errorCodes, equateValues, compareValues), errorCode => {
+            return flatMap(deduplicate<number>(errorCodes, equateValues, compareValues), errorCode => {
                 cancellationToken.throwIfCancellationRequested();
                 return codefix.getFixes({ errorCode, sourceFile, span, program, host, cancellationToken, formatContext, preferences });
             });