diff --git a/winsup/cygwin/ntdll.h b/winsup/cygwin/ntdll.h
index 0c6ad13dc..554e04665 100644
--- a/winsup/cygwin/ntdll.h
+++ b/winsup/cygwin/ntdll.h
@@ -1423,6 +1423,12 @@ extern "C"
   NTSTATUS NTAPI NtMapViewOfSection (HANDLE, HANDLE, PVOID *, ULONG_PTR, SIZE_T,
 				     PLARGE_INTEGER, PSIZE_T, SECTION_INHERIT,
 				     ULONG, ULONG);
+
+/* For the extended memory API. */
+#if __MINGW64_VERSION_MAJOR < 8
+#error "Version >= 8 of the w32api headers is required"
+#endif
+
   NTSTATUS NTAPI NtMapViewOfSectionEx (HANDLE, HANDLE, PVOID *, PLARGE_INTEGER,
 				       PSIZE_T, ULONG, ULONG,
 				       PMEM_EXTENDED_PARAMETER, ULONG);
diff --git a/winsup/cygwin/winlean.h b/winsup/cygwin/winlean.h
index 2ee4aaff4..2e2308eb6 100644
--- a/winsup/cygwin/winlean.h
+++ b/winsup/cygwin/winlean.h
@@ -99,47 +99,17 @@ details. */
 extern "C" {
 #endif
 
-/* Define extended memory API here as long as not available from mingw-w64. */
+/* For the extended memory API. */
+#if __MINGW64_VERSION_MAJOR < 8
+#error "Version >= 8 of the w32api headers is required"
+#endif
 
-typedef struct _MEM_ADDRESS_REQUIREMENTS
-{
-  PVOID LowestStartingAddress;
-  PVOID HighestEndingAddress;
-  SIZE_T Alignment;
-} MEM_ADDRESS_REQUIREMENTS, *PMEM_ADDRESS_REQUIREMENTS;
-
-typedef enum MEM_EXTENDED_PARAMETER_TYPE
-{
-  MemExtendedParameterInvalidType = 0,
-  MemExtendedParameterAddressRequirements,
-  MemExtendedParameterNumaNode,
-  MemExtendedParameterPartitionHandle,
-  MemExtendedParameterUserPhysicalHandle,
-  MemExtendedParameterAttributeFlags,
-  MemExtendedParameterMax
-} MEM_EXTENDED_PARAMETER_TYPE, *PMEM_EXTENDED_PARAMETER_TYPE;
-
-#define MEM_EXTENDED_PARAMETER_TYPE_BITS 8
-
-typedef struct DECLSPEC_ALIGN(8) MEM_EXTENDED_PARAMETER
-{
-  struct
-  {
-      DWORD64 Type : MEM_EXTENDED_PARAMETER_TYPE_BITS;
-      DWORD64 Reserved : 64 - MEM_EXTENDED_PARAMETER_TYPE_BITS;
-  };
-  union
-  {
-      DWORD64 ULong64;
-      PVOID Pointer;
-      SIZE_T Size;
-      HANDLE Handle;
-      DWORD ULong;
-  };
-} MEM_EXTENDED_PARAMETER, *PMEM_EXTENDED_PARAMETER;
-
-PVOID VirtualAlloc2 (HANDLE, PVOID, SIZE_T, ULONG, ULONG,
-		     PMEM_EXTENDED_PARAMETER, ULONG);
+/* VirtualAlloc2 is declared in <w32api/memoryapi.h> if NTDDI_VERSION
+   >= NTDDI_WIN10_RS4 (a compile-time condition).  But we need the
+   declaration unconditionally, even though the function will only be
+   executed on systems that support it (a run-time condition). */
+PVOID WINAPI VirtualAlloc2 (HANDLE, PVOID, SIZE_T, ULONG, ULONG,
+			    PMEM_EXTENDED_PARAMETER, ULONG);
 
 #ifdef __cplusplus
 }
diff --git a/winsup/utils/cygpath.cc b/winsup/utils/cygpath.cc
index aa9df3a21..bc5f11dd0 100644
--- a/winsup/utils/cygpath.cc
+++ b/winsup/utils/cygpath.cc
@@ -24,7 +24,6 @@ details. */
 #define _WIN32_WINNT 0x0a00
 #define WINVER 0x0a00
 #define NOCOMATTRIBUTE
-#define PMEM_EXTENDED_PARAMETER PVOID
 #include <windows.h>
 #include <userenv.h>
 #include <shlobj.h>
diff --git a/winsup/utils/ps.cc b/winsup/utils/ps.cc
index f3eb9e847..478ed8efd 100644
--- a/winsup/utils/ps.cc
+++ b/winsup/utils/ps.cc
@@ -6,7 +6,6 @@ This software is a copyrighted work licensed under the terms of the
 Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
 details. */
 
-#define PMEM_EXTENDED_PARAMETER PVOID
 #include <errno.h>
 #include <stdio.h>
 #include <locale.h>