diff --git a/HaveValidSnapshot.swift b/HaveValidSnapshot.swift
index f230017f..426d4260 100644
--- a/HaveValidSnapshot.swift
+++ b/HaveValidSnapshot.swift
@@ -118,12 +118,12 @@ func _getDefaultReferenceDirectory(_ sourceFileName: String) -> String {
         let folderPath = folderPathComponents.componentsJoinedByString("/")
     #endif
 
-    _setDefaultFailureDiffsDirectory(testTargetFolderPath: folderPath)
+    _setDefaultFailureDiffsDirectory(folderPath)
 
     return folderPath + "/ReferenceImages"
 }
 
-func _setDefaultFailureDiffsDirectory(testTargetFolderPath: String) {
+func _setDefaultFailureDiffsDirectory(_ testTargetFolderPath: String) {
     setenv("IMAGE_DIFF_DIR", "\(testTargetFolderPath)/FailureDiffs", 0)
 }