diff --git a/test/unittest/readertest.cpp b/test/unittest/readertest.cpp
index ac5a067..0973791 100644
--- a/test/unittest/readertest.cpp
+++ b/test/unittest/readertest.cpp
@@ -1832,6 +1832,10 @@ TEST(Reader, ParseNanAndInfinity) {
     TEST_NAN_INF("Infinity", inf);
     TEST_NAN_INF("-Inf", -inf);
     TEST_NAN_INF("-Infinity", -inf);
+    TEST_NAN_INF_ERROR(kParseErrorValueInvalid, "NInf", 1);
+    TEST_NAN_INF_ERROR(kParseErrorValueInvalid, "NaInf", 1);
+    TEST_NAN_INF_ERROR(kParseErrorValueInvalid, "INan", 1);
+    TEST_NAN_INF_ERROR(kParseErrorValueInvalid, "InNan", 1);
     TEST_NAN_INF_ERROR(kParseErrorValueInvalid, "nan", 1);
     TEST_NAN_INF_ERROR(kParseErrorValueInvalid, "-nan", 1);
     TEST_NAN_INF_ERROR(kParseErrorValueInvalid, "NAN", 1);