diff --git a/libvips/include/vips/internal.h b/libvips/include/vips/internal.h
index 992eee8b..7ca1a8bf 100644
--- a/libvips/include/vips/internal.h
+++ b/libvips/include/vips/internal.h
@@ -39,6 +39,39 @@
 extern "C" {
 #endif /*__cplusplus*/
 
+/* Try to make an O_BINARY and O_NOINHERIT ... sometimes need the leading '_'.
+ */
+#if defined(G_PLATFORM_WIN32) || defined(G_WITH_CYGWIN)
+# ifndef O_BINARY
+#  ifdef _O_BINARY
+#   define O_BINARY _O_BINARY
+#  endif /*_O_BINARY*/
+# endif /*!O_BINARY*/
+# ifndef O_NOINHERIT
+#  ifdef _O_NOINHERIT
+#   define O_NOINHERIT _O_NOINHERIT
+#  endif /*_O_NOINHERIT*/
+# endif /*!O_NOINHERIT*/
+#endif /*defined(G_PLATFORM_WIN32) || defined(G_WITH_CYGWIN)*/
+
+/* If we have O_BINARY, add it to a mode flags set.
+ */
+#ifdef O_BINARY
+# define BINARYIZE(M) ((M) | O_BINARY)
+#else /*!O_BINARY*/
+# define BINARYIZE(M) (M)
+#endif /*O_BINARY*/
+
+/* If we have O_CLOEXEC or O_NOINHERIT, add it to a mode flags set.
+ */
+#ifdef O_CLOEXEC
+# define CLOEXEC(M) ((M) | O_CLOEXEC)
+#elif defined(O_NOINHERIT)
+# define CLOEXEC(M) ((M) | O_NOINHERIT)
+#else /*!O_CLOEXEC && !O_NOINHERIT*/
+# define CLOEXEC(M) (M)
+#endif /*O_CLOEXEC*/
+
 /* << on an int is undefined in C if the int is negative. Imagine a machine
  * that uses 1s complement, for example.
  *
diff --git a/libvips/iofuncs/source.c b/libvips/iofuncs/source.c
index 86286f00..9747b508 100644
--- a/libvips/iofuncs/source.c
+++ b/libvips/iofuncs/source.c
@@ -69,46 +69,13 @@
 #include <fcntl.h>
 #include <unistd.h>
 
-#include <vips/vips.h>
-#include <vips/internal.h>
-#include <vips/debug.h>
-
 #ifdef G_OS_WIN32
 #include <io.h>
 #endif /*G_OS_WIN32*/
 
-/* Try to make an O_BINARY and O_NOINHERIT ... sometimes need the leading '_'.
- */
-#if defined(G_PLATFORM_WIN32) || defined(G_WITH_CYGWIN)
-#ifndef O_BINARY
-#ifdef _O_BINARY
-#define O_BINARY _O_BINARY
-#endif /*_O_BINARY*/
-#endif /*!O_BINARY*/
-#ifndef O_NOINHERIT
-#ifdef _O_NOINHERIT
-#define O_NOINHERIT _O_NOINHERIT
-#endif /*_O_NOINHERIT*/
-#endif /*!O_NOINHERIT*/
-#endif /*defined(G_PLATFORM_WIN32) || defined(G_WITH_CYGWIN)*/
-
-/* If we have O_BINARY, add it to a mode flags set.
- */
-#ifdef O_BINARY
-#define BINARYIZE(M) ((M) | O_BINARY)
-#else /*!O_BINARY*/
-#define BINARYIZE(M) (M)
-#endif /*O_BINARY*/
-
-/* If we have O_CLOEXEC or O_NOINHERIT, add it to a mode flags set.
- */
-#ifdef O_CLOEXEC
-#define CLOEXEC(M) ((M) | O_CLOEXEC)
-#elif defined(O_NOINHERIT)
-#define CLOEXEC(M) ((M) | O_NOINHERIT)
-#else /*!O_CLOEXEC && !O_NOINHERIT*/
-#define CLOEXEC(M) (M)
-#endif /*O_CLOEXEC*/
+#include <vips/vips.h>
+#include <vips/debug.h>
+#include <vips/internal.h>
 
 #define MODE_READ CLOEXEC (BINARYIZE (O_RDONLY))
 
diff --git a/libvips/iofuncs/target.c b/libvips/iofuncs/target.c
index 3dbcec10..d61abda9 100644
--- a/libvips/iofuncs/target.c
+++ b/libvips/iofuncs/target.c
@@ -56,46 +56,13 @@
 #include <fcntl.h>
 #include <unistd.h>
 
-#include <vips/vips.h>
-#include <vips/internal.h>
-#include <vips/debug.h>
-
 #ifdef G_OS_WIN32
 #include <io.h>
 #endif /*G_OS_WIN32*/
 
-/* Try to make an O_BINARY and O_NOINHERIT ... sometimes need the leading '_'.
- */
-#if defined(G_PLATFORM_WIN32) || defined(G_WITH_CYGWIN)
-#ifndef O_BINARY
-#ifdef _O_BINARY
-#define O_BINARY _O_BINARY
-#endif /*_O_BINARY*/
-#endif /*!O_BINARY*/
-#ifndef O_NOINHERIT
-#ifdef _O_NOINHERIT
-#define O_NOINHERIT _O_NOINHERIT
-#endif /*_O_NOINHERIT*/
-#endif /*!O_NOINHERIT*/
-#endif /*defined(G_PLATFORM_WIN32) || defined(G_WITH_CYGWIN)*/
-
-/* If we have O_BINARY, add it to a mode flags set.
- */
-#ifdef O_BINARY
-#define BINARYIZE(M) ((M) | O_BINARY)
-#else /*!O_BINARY*/
-#define BINARYIZE(M) (M)
-#endif /*O_BINARY*/
-
-/* If we have O_CLOEXEC or O_NOINHERIT, add it to a mode flags set.
- */
-#ifdef O_CLOEXEC
-#define CLOEXEC(M) ((M) | O_CLOEXEC)
-#elif defined(O_NOINHERIT)
-#define CLOEXEC(M) ((M) | O_NOINHERIT)
-#else /*!O_CLOEXEC && !O_NOINHERIT*/
-#define CLOEXEC(M) (M)
-#endif /*O_CLOEXEC*/
+#include <vips/vips.h>
+#include <vips/debug.h>
+#include <vips/internal.h>
 
 #define MODE_WRITE CLOEXEC (BINARYIZE (O_WRONLY | O_CREAT | O_TRUNC))
 
diff --git a/libvips/iofuncs/util.c b/libvips/iofuncs/util.c
index 471ae430..57cce044 100644
--- a/libvips/iofuncs/util.c
+++ b/libvips/iofuncs/util.c
@@ -53,51 +53,18 @@
 #endif /*HAVE_IO_H*/
 #include <fcntl.h>
 
-#include <vips/vips.h>
-#include <vips/debug.h>
-#include <vips/internal.h>
-
 #ifdef G_OS_WIN32
 #include <windows.h>
 #endif /*G_OS_WIN32*/
 
+#include <vips/vips.h>
+#include <vips/debug.h>
+#include <vips/internal.h>
+
 /* Temp buffer for snprintf() layer on old systems.
  */
 #define MAX_BUF (100000)
 
-/* Try to make an O_BINARY and O_NOINHERIT ... sometimes need the leading '_'.
- */
-#if defined(G_PLATFORM_WIN32) || defined(G_WITH_CYGWIN)
-#ifndef O_BINARY
-#ifdef _O_BINARY
-#define O_BINARY _O_BINARY
-#endif /*_O_BINARY*/
-#endif /*!O_BINARY*/
-#ifndef O_NOINHERIT
-#ifdef _O_NOINHERIT
-#define O_NOINHERIT _O_NOINHERIT
-#endif /*_O_NOINHERIT*/
-#endif /*!O_NOINHERIT*/
-#endif /*defined(G_PLATFORM_WIN32) || defined(G_WITH_CYGWIN)*/
-
-/* If we have O_BINARY, add it to a mode flags set.
- */
-#ifdef O_BINARY
-#define BINARYIZE(M) ((M) | O_BINARY)
-#else /*!O_BINARY*/
-#define BINARYIZE(M) (M)
-#endif /*O_BINARY*/
-
-/* If we have O_CLOEXEC or O_NOINHERIT, add it to a mode flags set.
- */
-#ifdef O_CLOEXEC
-#define CLOEXEC(M) ((M) | O_CLOEXEC)
-#elif defined(O_NOINHERIT)
-#define CLOEXEC(M) ((M) | O_NOINHERIT)
-#else /*!O_CLOEXEC && !O_NOINHERIT*/
-#define CLOEXEC(M) (M)
-#endif /*O_CLOEXEC*/
-
 #define MODE_READ CLOEXEC (BINARYIZE (O_RDONLY))
 
 /* Test two lists for eqality.
diff --git a/libvips/iofuncs/vips.c b/libvips/iofuncs/vips.c
index e9ab400d..59d5a0d7 100644
--- a/libvips/iofuncs/vips.c
+++ b/libvips/iofuncs/vips.c
@@ -94,9 +94,13 @@
 #include <expat.h>
 #include <errno.h>
 
+#ifdef G_OS_WIN32
+#include <windows.h>
+#endif /*G_OS_WIN32*/
+
 #include <vips/vips.h>
-#include <vips/internal.h>
 #include <vips/debug.h>
+#include <vips/internal.h>
 
 /**
  * SECTION: vips
@@ -113,40 +117,7 @@
  * world. See vips_init() and vips_guess_prefix().
  */
 
-/* Try to make an O_BINARY and O_NOINHERIT ... sometimes need the leading '_'.
- */
-#if defined(G_PLATFORM_WIN32) || defined(G_WITH_CYGWIN)
-#ifndef O_BINARY
-#ifdef _O_BINARY
-#define O_BINARY _O_BINARY
-#endif /*_O_BINARY*/
-#endif /*!O_BINARY*/
-#ifndef O_NOINHERIT
-#ifdef _O_NOINHERIT
-#define O_NOINHERIT _O_NOINHERIT
-#endif /*_O_NOINHERIT*/
-#endif /*!O_NOINHERIT*/
-#endif /*defined(G_PLATFORM_WIN32) || defined(G_WITH_CYGWIN)*/
-
-/* If we have O_BINARY, add it to a mode flags set.
- */
-#ifdef O_BINARY
-#define BINARYIZE(M) ((M) | O_BINARY)
-#else /*!O_BINARY*/
-#define BINARYIZE(M) (M)
-#endif /*O_BINARY*/
-
-/* If we have O_CLOEXEC or O_NOINHERIT, add it to a mode flags set.
- */
-#ifdef O_CLOEXEC
-#define CLOEXEC(M) ((M) | O_CLOEXEC)
-#elif defined(O_NOINHERIT)
-#define CLOEXEC(M) ((M) | O_NOINHERIT)
-#else /*!O_CLOEXEC && !O_NOINHERIT*/
-#define CLOEXEC(M) (M)
-#endif /*O_CLOEXEC*/
-
-/* Open mode for image write ... on some systems, have to set BINARY too.
+/* Open mode for image write.
  *
  * We use O_RDWR not O_WRONLY since after writing we may want to rewind the 
  * image and read from it.