diff --git a/test/src/unit-conversions.cpp b/test/src/unit-conversions.cpp
index 1a5033df..9d48e29d 100644
--- a/test/src/unit-conversions.cpp
+++ b/test/src/unit-conversions.cpp
@@ -1537,31 +1537,6 @@ NLOHMANN_JSON_SERIALIZE_ENUM(TaskState,
     {TS_COMPLETED, "completed"},
 })
 
-namespace
-{
-// Helper struct to test whether compile error does not trigger upon
-// conversion of an enum in the presence of non-member operator== for
-// user-defined type with "non default" from_json function (#1647).
-struct NonDefaultFromJsonStruct { };
-
-inline bool operator== (NonDefaultFromJsonStruct const& lhs, NonDefaultFromJsonStruct const& rhs)
-{
-    return true;
-}
-}
-
-namespace nlohmann
-{
-template <>
-struct adl_serializer<NonDefaultFromJsonStruct>
-{
-    static NonDefaultFromJsonStruct from_json (json const& j)
-    {
-        return {};
-    }
-};
-}
-
 TEST_CASE("JSON to enum mapping")
 {
     SECTION("enum class")
diff --git a/test/src/unit-regression.cpp b/test/src/unit-regression.cpp
index 0c75dcbc..869d6cc8 100644
--- a/test/src/unit-regression.cpp
+++ b/test/src/unit-regression.cpp
@@ -159,6 +159,38 @@ bool operator==(Data const& lhs, Data const& rhs)
 
 using float_json = nlohmann::basic_json<std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t, float>;
 
+/////////////////////////////////////////////////////////////////////
+// for #1647
+/////////////////////////////////////////////////////////////////////
+namespace
+{
+struct NonDefaultFromJsonStruct { };
+
+inline bool operator== (NonDefaultFromJsonStruct const& lhs, NonDefaultFromJsonStruct const& rhs)
+{
+    return true;
+}
+
+enum class for_1647 { one, two };
+
+NLOHMANN_JSON_SERIALIZE_ENUM(for_1647,
+{
+    {for_1647::one, "one"},
+    {for_1647::two, "two"},
+})
+}
+
+namespace nlohmann
+{
+template <>
+struct adl_serializer<NonDefaultFromJsonStruct>
+{
+    static NonDefaultFromJsonStruct from_json (json const& j)
+    {
+        return {};
+    }
+};
+}
 
 TEST_CASE("regression tests")
 {
@@ -1820,6 +1852,12 @@ TEST_CASE("regression tests")
         CHECK(j.contains(jptr1));
         CHECK(j.contains(jptr2));
     }
+
+    SECTION("issue #1647 - compile error when deserializing enum if both non-default from_json and non-member operator== exists for other type")
+    {
+        auto val = nlohmann::json("one").get<for_1647>();
+        CHECK(val == for_1647::one);
+    }
 }
 
 #if not defined(JSON_NOEXCEPTION)