diff --git a/test/src/unit-conversions.cpp b/test/src/unit-conversions.cpp
index 7a502089..5259acbb 100644
--- a/test/src/unit-conversions.cpp
+++ b/test/src/unit-conversions.cpp
@@ -438,7 +438,7 @@ TEST_CASE("value conversion")
         std::nullptr_t n;
         json j(n);
 
-        std::nullptr_t n2 = j;
+        std::nullptr_t n2 = (std::nullptr_t)j;
         CHECK(n2 == n);
     }