diff --git a/stdlib/public/Platform/ucrt.modulemap b/stdlib/public/Platform/ucrt.modulemap
index 68bcbfeddfeec..ad440863ad8c6 100644
--- a/stdlib/public/Platform/ucrt.modulemap
+++ b/stdlib/public/Platform/ucrt.modulemap
@@ -10,16 +10,13 @@
 //
 //===----------------------------------------------------------------------===//
 
+module _complex [system] {
+  header "complex.h"
+  export *
+}
+
 module ucrt [system] {
   module C {
-    module complex {
-      /* disallow the header in C++ mode as it forwards to `ccomplex`.  */
-      requires !cplusplus
-
-      header "complex.h"
-      export *
-    }
-
     module ctype {
       header "ctype.h"
       export *
diff --git a/stdlib/public/Platform/ucrt.swift b/stdlib/public/Platform/ucrt.swift
index 80181db44d5cf..09eaf11c9ab3d 100644
--- a/stdlib/public/Platform/ucrt.swift
+++ b/stdlib/public/Platform/ucrt.swift
@@ -11,6 +11,8 @@
 //===----------------------------------------------------------------------===//
 
 @_exported import ucrt // Clang module
+// Extra clang module that's split out from ucrt:
+@_exported import _complex
 
 @available(swift, deprecated: 3.0, message: "Please use 'Double.pi' or '.pi' to get the value of correct type and avoid casting.")
 public let M_PI = Double.pi
diff --git a/test/Interop/Cxx/stdlib/foundation-and-std-module.swift b/test/Interop/Cxx/stdlib/foundation-and-std-module.swift
index 8dcc93b45c710..29d05d94e1462 100644
--- a/test/Interop/Cxx/stdlib/foundation-and-std-module.swift
+++ b/test/Interop/Cxx/stdlib/foundation-and-std-module.swift
@@ -3,14 +3,12 @@
 // RUN: %target-swift-frontend %s -c -enable-experimental-cxx-interop -Xcc -std=c++17 -Xcc -fmodules-cache-path=%t
 // RUN: %target-swift-frontend %s -c -enable-experimental-cxx-interop -Xcc -std=c++20 -Xcc -fmodules-cache-path=%t
 
-// RUN: find %t | %FileCheck %s
-
 // RUN: %empty-directory(%t)
 
 // RUN: %target-swift-frontend %s -c -enable-experimental-cxx-interop -Xcc -std=c++17 -Xcc -fmodules-cache-path=%t -DADD_CXXSTDLIB
 // RUN: %target-swift-frontend %s -c -enable-experimental-cxx-interop -Xcc -std=c++20 -Xcc -fmodules-cache-path=%t -DADD_CXXSTDLIB
 
-// REQUIRES: OS=macosx || OS=linux-gnu
+// RUN: %{python} -c "import os, glob; print('\n'.join(glob.glob(os.path.join('%/t', '**', '*.pcm'), recursive=True)))" | %FileCheck %s
 
 #if canImport(Foundation)
 import Foundation
diff --git a/test/stdlib/CRTWinAPIs.swift b/test/stdlib/CRTWinAPIs.swift
new file mode 100644
index 0000000000000..07e8fb54054c7
--- /dev/null
+++ b/test/stdlib/CRTWinAPIs.swift
@@ -0,0 +1,12 @@
+// RUN: %target-typecheck-verify-swift
+// REQUIRES: OS=windows-msvc
+
+// This file has CRT-specific C stdlib tests, that use
+// some APIs present only in CRT.
+
+import CRT
+
+func complexFunctionsAvailableInSwift() {
+  let complexValue = _Cbuild(1.0, 2.0) // Construct a complex double using MSVC-specific API.
+  let _ = creal(complexValue)
+}