diff --git a/Tests/XcodeGenKitTests/PerformanceTests.swift b/Tests/XcodeGenKitTests/PerformanceTests.swift
index 11058593..6ecaec3d 100644
--- a/Tests/XcodeGenKitTests/PerformanceTests.swift
+++ b/Tests/XcodeGenKitTests/PerformanceTests.swift
@@ -22,6 +22,7 @@ class GeneratedPerformanceTests: XCTestCase {
         let generator = ProjectGenerator(project: project)
         let xcodeProject = try generator.generateXcodeProject()
         self.measure {
+            xcodeProject.pbxproj.invalidateUUIDs()
             try! xcodeProject.write(path: project.projectPath)
         }
     }
@@ -50,6 +51,7 @@ class FixturePerformanceTests: XCTestCase {
         let generator = ProjectGenerator(project: project)
         let xcodeProject = try generator.generateXcodeProject()
         self.measure {
+            xcodeProject.pbxproj.invalidateUUIDs()
             try! xcodeProject.write(path: project.projectPath)
         }
     }