diff --git a/ext/tidy/config.m4 b/ext/tidy/config.m4
index ff27bd1aaa9..da9351e9912 100644
--- a/ext/tidy/config.m4
+++ b/ext/tidy/config.m4
@@ -25,6 +25,14 @@ if test "$PHP_TIDY" != "no"; then
 
   if test -z "$TIDY_DIR"; then
     AC_MSG_ERROR(Cannot find libtidy)
+  else
+    dnl Check for tidybuffio.h (as opposed to simply buffio.h)
+    dnl which indicates that we are building against tidy-html5
+    dnl and not the legacy htmltidy. The two are compatible,
+    dnl except for with regard to this header file.
+    if test -f "$TIDY_INCDIR/tidybuffio.h"; then
+      AC_DEFINE(HAVE_TIDYBUFFIO_H,1,[defined if tidybuffio.h exists])
+    fi
   fi
 
   TIDY_LIBDIR=$TIDY_DIR/$PHP_LIBDIR
diff --git a/ext/tidy/tidy.c b/ext/tidy/tidy.c
index 0537c576c70..d6461bd5136 100644
--- a/ext/tidy/tidy.c
+++ b/ext/tidy/tidy.c
@@ -31,7 +31,12 @@
 #include "ext/standard/info.h"
 
 #include "tidy.h"
+
+#if HAVE_TIDYBUFFIO_H
+#include "tidybuffio.h"
+#else
 #include "buffio.h"
+#endif
 
 /* compatibility with older versions of libtidy */
 #ifndef TIDY_CALL