diff --git a/contrib/nightly_tests/idnareject.conf b/contrib/nightly_tests/idnareject.conf
new file mode 100644
index 0000000..dbcbe69
--- /dev/null
+++ b/contrib/nightly_tests/idnareject.conf
@@ -0,0 +1,4 @@
+
+set(CTEST_BUILD_OPTIONS "${CTEST_BUILD_OPTIONS} -DDIAMID_IDNA_REJECT:BOOL=ON")
+
+set(CTEST_BUILD_NAME "IDNA Reject")