diff --git a/m4/ac_pkg_cython.m4 b/m4/ac_pkg_cython.m4
index 3b4c9a7..e0af96a 100644
--- a/m4/ac_pkg_cython.m4
+++ b/m4/ac_pkg_cython.m4
@@ -1,8 +1,8 @@
 
 AC_DEFUN([AC_PROG_CYTHON],[
-        AC_PATH_PROG([CYTHON],[cython])
+        AC_PATH_PROGS([CYTHON],[cython cython3])
         if test -z "$CYTHON" ; then
-                AC_MSG_WARN([cannot find 'cython' program. You should look at http://www.cython.org] or install your distribution specific cython package.)
+                AC_MSG_WARN([Unable to find 'cython' or 'cython3' program. You should look at https://cython.org or install your distribution specific cython package.])
                 CYTHON=false
         elif test -n "$1" ; then
                 AC_MSG_CHECKING([for Cython version])
@@ -59,7 +59,7 @@
                                 CYTHON='echo "Error: Cython version >= $1 is required.  You have '"$cython_version"'.  You should look at http://www.cython.org" ; false'
                         fi
                 else
-                        AC_MSG_WARN([cannot determine Cython version])
+                        AC_MSG_WARN([Unable to determine Cython version])
                         CYTHON=false
                 fi
         fi