diff --git a/include/nlohmann/detail/conversions/from_json.hpp b/include/nlohmann/detail/conversions/from_json.hpp
index a51cb53db..d0e024687 100644
--- a/include/nlohmann/detail/conversions/from_json.hpp
+++ b/include/nlohmann/detail/conversions/from_json.hpp
@@ -44,6 +44,7 @@ inline void from_json(const BasicJsonType& j, typename std::nullptr_t& n)
 }
 
 #ifdef JSON_HAS_CPP_17
+#ifndef JSON_USE_IMPLICIT_CONVERSIONS
 template<typename BasicJsonType, typename T>
 void from_json(const BasicJsonType& j, std::optional<T>& opt)
 {
@@ -56,7 +57,9 @@ void from_json(const BasicJsonType& j, std::optional<T>& opt)
         opt.emplace(j.template get<T>());
     }
 }
-#endif
+
+#endif // JSON_USE_IMPLICIT_CONVERSIONS
+#endif // JSON_HAS_CPP_17
 
 // overloads for basic_json template parameters
 template < typename BasicJsonType, typename ArithmeticType,
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 6940d479b..86b067057 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -4616,6 +4616,7 @@ inline void from_json(const BasicJsonType& j, typename std::nullptr_t& n)
 }
 
 #ifdef JSON_HAS_CPP_17
+#ifndef JSON_USE_IMPLICIT_CONVERSIONS
 template<typename BasicJsonType, typename T>
 void from_json(const BasicJsonType& j, std::optional<T>& opt)
 {
@@ -4628,7 +4629,9 @@ void from_json(const BasicJsonType& j, std::optional<T>& opt)
         opt.emplace(j.template get<T>());
     }
 }
-#endif
+
+#endif // JSON_USE_IMPLICIT_CONVERSIONS
+#endif // JSON_HAS_CPP_17
 
 // overloads for basic_json template parameters
 template < typename BasicJsonType, typename ArithmeticType,
diff --git a/tests/src/unit-conversions.cpp b/tests/src/unit-conversions.cpp
index 939909ec9..2ba69d83c 100644
--- a/tests/src/unit-conversions.cpp
+++ b/tests/src/unit-conversions.cpp
@@ -1570,6 +1570,7 @@ TEST_CASE("JSON to enum mapping")
 }
 
 #ifdef JSON_HAS_CPP_17
+#ifndef JSON_USE_IMPLICIT_CONVERSIONS
 TEST_CASE("std::optional")
 {
     SECTION("null")
@@ -1605,7 +1606,7 @@ TEST_CASE("std::optional")
         std::optional<int> opt_int = 1;
 
         CHECK(json(opt_int) == j_number);
-        CHECK(std::optional<int>(j_number) == opt_int);
+        CHECK(j_number.get<std::optional<int>>() == opt_int);
     }
 
     SECTION("array")
@@ -1614,7 +1615,7 @@ TEST_CASE("std::optional")
         std::vector<std::optional<int>> opt_array = {{1, 2, std::nullopt}};
 
         CHECK(json(opt_array) == j_array);
-        CHECK(std::vector<std::optional<int>>(j_array) == opt_array);
+        CHECK(j_array.get<std::vector<std::optional<int>>>() == opt_array);
     }
 
     SECTION("object")
@@ -1627,6 +1628,7 @@ TEST_CASE("std::optional")
     }
 }
 #endif
+#endif
 
 #ifdef JSON_HAS_CPP_17
     #undef JSON_HAS_CPP_17