diff --git a/base.cabal b/base.cabal
--- a/base.cabal
+++ b/base.cabal
@@ -1,6 +1,6 @@
 cabal-version:  3.0
 name:           base
-version:        4.17.1.0
+version:        4.17.2.0
 -- NOTE: Don't forget to update ./changelog.md
 
 license:        BSD-3-Clause
@@ -377,6 +377,7 @@
     if os(windows)
         -- Windows requires some extra libraries for linking because the RTS
         -- is no longer re-exporting them.
+        -- mingwex: provides GNU POSIX extensions that aren't provided by ucrt.
         -- mingw32: Unfortunately required because of a resource leak between
         --          mingwex and mingw32. the __math_err symbol is defined in
         --          mingw32 which is required by mingwex.
@@ -389,7 +390,7 @@
         -- advapi32: provides advanced kernel functions
         extra-libraries:
             wsock32, user32, shell32, mingw32, kernel32, advapi32,
-            ws2_32, shlwapi, ole32, rpcrt4, ntdll
+            mingwex, ws2_32, shlwapi, ole32, rpcrt4, ntdll
         -- Minimum supported Windows version.
         -- These numbers can be found at:
         --  https://msdn.microsoft.com/en-us/library/windows/desktop/aa383745(v=vs.85).aspx
diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,11 @@
 # Changelog for [`base` package](http://hackage.haskell.org/package/base)
 
+## 4.17.2.0 *August 2023*
+
+   * Restore `mingwex` dependency on Windows (#23309).
+
+   * Fix an incorrect CPP guard on `darwin_HOST_OS`.
+
 ## 4.17.1.0 *April 2023*
 
    * Remove `mingwex` dependency on Windows (#22166).
diff --git a/include/HsBase.h b/include/HsBase.h
--- a/include/HsBase.h
+++ b/include/HsBase.h
@@ -543,7 +543,7 @@
 }
 #endif
 
-#if darwin_HOST_OS
+#if defined(darwin_HOST_OS)
 // You should not access _environ directly on Darwin in a bundle/shared library.
 // See #2458 and http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man7/environ.7.html
 #include <crt_externs.h>