diff -u im.orig/src/libtiff/tiffiop.h im.new/src/libtiff/tiffiop.h
--- im.orig/src/libtiff/tiffiop.h	2017-06-01 15:19:56.752324700 +0200
+++ im.new/src/libtiff/tiffiop.h	2017-06-01 15:35:20.446140300 +0200
@@ -59,7 +59,7 @@
 */
 #endif
 
-#if defined(WIN32) && !defined(__CYGWIN__)
+#if defined(WIN32) && !defined(__CYGWIN__) && !defined(__USE_MINGW_ANSI_STDIO)
 #define snprintf _snprintf
 #if _MSC_VER >= 1900 /* IMLIB vc14 */
 #undef snprintf