--- a/gecode.m4
+++ b/gecode.m4
@@ -1321,8 +1321,8 @@
   AC_ARG_ENABLE([qt],
     AS_HELP_STRING([--enable-qt],
       [build with Qt support, requires at least Qt 4.3 @<:@default=yes@:>@]))
-  AC_CHECK_PROGS(QMAKE, [qmake-qt4 qmake])
-  AC_CHECK_PROGS(MOC, [moc-qt4 moc])
+  AC_CHECK_PROGS(QMAKE, [qmake-qt4 qmake qmake6])
+  AC_CHECK_PROGS(MOC, [moc-qt4 moc], [], [/usr/bin:/bin:/usr/lib/qt6/libexec])
   AC_MSG_CHECKING(whether to build with Qt support)
   if test "${enable_qt:-yes}" = "yes"; then
     if test "${QMAKE}x" = "x" -o "${MOC}x" = "x"; then
