diff --git a/test/Interpreter/SDK/FoundationDiagnostics.swift b/test/Interpreter/SDK/FoundationDiagnostics.swift
deleted file mode 100644
index fbfc17f862cc8..0000000000000
--- a/test/Interpreter/SDK/FoundationDiagnostics.swift
+++ /dev/null
@@ -1,10 +0,0 @@
-// RUN: %target-swift-frontend %s -typecheck -verify
-
-// REQUIRES: objc_interop
-
-import Foundation
-
-func encode(_ string: String) {
-  _ = string.cString(using: NSUTF8StringEncoding) // expected-error {{'NSUTF8StringEncoding' has been renamed to 'String.Encoding.utf8'}} {{29-49=String.Encoding.utf8}}
-  let _: NSStringEncoding? = nil // expected-error {{'NSStringEncoding' has been renamed to 'String.Encoding'}} {{10-26=String.Encoding}}
-}
diff --git a/test/Interpreter/SDK/Foundation_NSRect.swift b/test/Interpreter/SDK/Foundation_NSRect.swift
index fbea20b257399..cdf57f73fab15 100644
--- a/test/Interpreter/SDK/Foundation_NSRect.swift
+++ b/test/Interpreter/SDK/Foundation_NSRect.swift
@@ -4,7 +4,9 @@
 // iOS doesn't have NSRect. iOS and OS X CGRect is tested elsewhere.
 // REQUIRES: OS=macosx
 
-import Foundation
+import CoreImage
+
+_ = JSONDecoder()
 
 func printRect(_ r: NSRect) {
   // FIXME: Constraint checker takes too long to typecheck this as an
diff --git a/test/Interpreter/SDK/Quartz_without_Foundation.swift b/test/Interpreter/SDK/Quartz_without_Foundation.swift
deleted file mode 100644
index 446ae40163355..0000000000000
--- a/test/Interpreter/SDK/Quartz_without_Foundation.swift
+++ /dev/null
@@ -1,10 +0,0 @@
-// RUN: %target-run-simple-swift | %FileCheck %s
-// REQUIRES: executable_test
-// REQUIRES: OS=macosx
-
-import QuartzCore
-// Do NOT add anything that publicly imports Foundation here!
-
-var v = CIVector(x:7);
-// CHECK: x = 7
-print("x = \(v.x)")
diff --git a/test/Interpreter/SDK/objc_implicit_inner_pointer.swift b/test/Interpreter/SDK/objc_implicit_inner_pointer.swift
index 77d2c7de236ff..a2227a213537c 100644
--- a/test/Interpreter/SDK/objc_implicit_inner_pointer.swift
+++ b/test/Interpreter/SDK/objc_implicit_inner_pointer.swift
@@ -7,6 +7,10 @@
 // REQUIRES: executable_test
 // REQUIRES: objc_interop
 
+import Foundation
+
+_ = JSONDecoder()
+
 do {
   // The lifetime of Foo() currently gets extended using autorelease.
   autoreleasepool {
diff --git a/test/Interpreter/SDK/objc_inner_pointer.swift b/test/Interpreter/SDK/objc_inner_pointer.swift
index 44f893b3fecf6..710404075ac0d 100644
--- a/test/Interpreter/SDK/objc_inner_pointer.swift
+++ b/test/Interpreter/SDK/objc_inner_pointer.swift
@@ -4,6 +4,8 @@
 // REQUIRES: objc_interop
 
 import Foundation
+ 
+_ = JSONDecoder()
 
 class Canary: NSObject {
   deinit {
diff --git a/test/Interpreter/SDK/objc_unowned.swift b/test/Interpreter/SDK/objc_unowned.swift
index fc75dc0ca0b3b..cd862541d9500 100644
--- a/test/Interpreter/SDK/objc_unowned.swift
+++ b/test/Interpreter/SDK/objc_unowned.swift
@@ -5,6 +5,8 @@
 
 import Foundation
 
+_ = JSONDecoder()
+
 let x = NSObject()
 unowned let y = x
 
diff --git a/test/stdlib/NSStringAPI.swift b/test/stdlib/NSStringAPI.swift
index a1cdc280f6592..c29ca48ce2269 100644
--- a/test/stdlib/NSStringAPI.swift
+++ b/test/stdlib/NSStringAPI.swift
@@ -210,9 +210,10 @@ NSStringAPIs.test("init(contentsOf:usedEncoding:error:)") {
 }
 
 NSStringAPIs.test("init(cString_:encoding:)") {
-  expectEqual("foo, a basmati bar!",
-      String(cString: 
-          "foo, a basmati bar!", encoding: String.defaultCStringEncoding))
+  "foo, a basmati bar!".withCString {
+    expectEqual("foo, a basmati bar!",
+        String(cString: $0, encoding: String.defaultCStringEncoding))
+  }
 }
 
 NSStringAPIs.test("init(utf8String:)") {
diff --git a/validation-test/compiler_crashers_2_fixed/rdar81590807.swift b/validation-test/compiler_crashers_2_fixed/rdar81590807.swift
index 2d82ccc13825c..46170c5e94aae 100644
--- a/validation-test/compiler_crashers_2_fixed/rdar81590807.swift
+++ b/validation-test/compiler_crashers_2_fixed/rdar81590807.swift
@@ -48,6 +48,7 @@ func run(on object: PFXObject) async throws {
 
 @main struct Main {
   static func main() async throws {
+    _ = JSONDecoder()
     let object = PFXObject()
     try await run(on: object)
   }