diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 4d2480ffef9..b4339e78f2a 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -711,8 +711,8 @@ namespace ts {
         }
 
         return {
-            fileNames: wildcardFiles.reduce(addFileToOutput, literalFiles.reduce(addFileToOutput, [])),
-            wildcardDirectories: wildcardDirectories.reduce<Map<WatchDirectoryFlags>>(addDirectoryToOutput, {}),
+            fileNames: wildcardFiles.reduceProperties(addFileToOutput, literalFiles.reduceProperties(addFileToOutput, [])),
+            wildcardDirectories: wildcardDirectories.reduceProperties<Map<WatchDirectoryFlags>>(addDirectoryToOutput, {}),
         };
     }
 
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 998766e8d9d..3e6981996e1 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -25,7 +25,7 @@ namespace ts {
             contains,
             remove,
             forEachValue: forEachValueInMap,
-            reduce,
+            reduceProperties: reducePropertiesInMap,
             clear,
             mergeFrom
         };
@@ -36,7 +36,7 @@ namespace ts {
             }
         }
 
-        function reduce<U>(callback: (memo: U, value: T, key: Path) => U, initial: U) {
+        function reducePropertiesInMap<U>(callback: (memo: U, value: T, key: Path) => U, initial: U) {
             return reduceProperties(files, callback, initial);
         }
 
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 4b84c27be99..4c62904f4e8 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -14,7 +14,7 @@ namespace ts {
         remove(fileName: Path): void;
 
         forEachValue(f: (key: Path, v: T) => void): void;
-        reduce<U>(f: (memo: U, value: T, key: Path) => U, initial: U): U;
+        reduceProperties<U>(f: (memo: U, value: T, key: Path) => U, initial: U): U;
         mergeFrom(other: FileMap<T>): void;
         clear(): void;
     }