Index: trunk/m4/api_python.m4
===================================================================
--- trunk/m4/api_python.m4	(revision 8844)
+++ trunk/m4/api_python.m4	(revision 8845)
@@ -1,48 +1,49 @@
 dnl api_python.m4 -- checks for Python/Python API library
 dnl
 
 AC_DEFUN([WO_PROG_PYTHON_API],
 [dnl
 AC_REQUIRE([AX_PYTHON_DEVEL])
 
 AC_ARG_ENABLE([python],
   [AS_HELP_STRING([--enable-python],
     [enable PYTHON/Cython API for WHIZARD [[no]]])],
   [], [enable_python="no"])
 
 AC_PATH_PROG(cython_exe,[cython],[no])
+AC_PATH_PROG(cython3_exe,[cython3],[no])
 
 if test "$enable_python" = "yes"; then
   AC_MSG_CHECKING([for PYTHON API])
   if test "$PYTHON_API" = "yes"; then
-    if test "$cython_exe" = "no"; then
+    if test "$cython3_exe" = "no" -a "$cython_exe" = "no"; then
       enable_python="no"
       AC_MSG_RESULT([(disabled)])
       AC_MSG_WARN([******************
 The Python interface requires Cython.
 It will be disabled. ****************])
     else
       AC_MSG_RESULT([(enabled)])
     fi
   else
     enable_python="no"
     AC_MSG_RESULT([(disabled)])
     AC_MSG_WARN([**********************
 The Python interface requires Python 3.5.
 It will be disabled. ********************])
   fi
 else
   AC_MSG_CHECKING([for PYTHON API])
   AC_MSG_RESULT([(disabled)])
 fi
 
 if test "$enable_python" = "yes"; then
    PYTHON_API_AVAILABLE_FLAG=".true."
 else
    PYTHON_API_AVAILABLE_FLAG=".false."
 fi
 AC_SUBST([PYTHON_API_AVAILABLE_FLAG])
 
 AM_CONDITIONAL([PYTHON_API_AVAILABLE], [test "$enable_python" = "yes"])
 ])