diff --git a/.travis.yml b/.travis.yml
index 280c2c06c0..d5811eebd8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -218,6 +218,17 @@ matrix:
         sources: ['ubuntu-toolchain-r-test']
         packages: ['g++-9', 'ninja-build']
 
+  - os: linux
+    compiler: gcc
+    env:
+      - COMPILER=g++-9
+      - CXXFLAGS=-std=c++17
+      - CMAKE_CXX_STANDARD=17
+    addons:
+      apt:
+        sources: ['ubuntu-toolchain-r-test']
+        packages: ['g++-9', 'ninja-build']
+
   # Linux / Clang
 
   - os: linux
@@ -328,7 +339,11 @@ script:
 
   # compile and execute unit tests
   - mkdir -p build && cd build
-  - cmake .. ${CMAKE_OPTIONS} -DJSON_MultipleHeaders=${MULTIPLE_HEADERS} -GNinja && cmake --build . --config Release
+  - if [[ "${CMAKE_CXX_STANDARD}" != "" ]]; then
+    cmake .. ${CMAKE_OPTIONS} -DJSON_MultipleHeaders=${MULTIPLE_HEADERS} -DCMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD} -GNinja && cmake --build . --config Release ;
+    else
+    cmake .. ${CMAKE_OPTIONS} -DJSON_MultipleHeaders=${MULTIPLE_HEADERS} -GNinja && cmake --build . --config Release ;
+    fi
   - ctest -C Release --timeout 2700 -V -j
   - cd ..
 
diff --git a/test/src/unit-conversions.cpp b/test/src/unit-conversions.cpp
index 2fce369616..476a2149d9 100644
--- a/test/src/unit-conversions.cpp
+++ b/test/src/unit-conversions.cpp
@@ -1710,7 +1710,8 @@ TEST_CASE("std::optional")
         std::optional<std::string> opt_null;
 
         CHECK(json(opt_null) == j_null);
-        CHECK(std::optional<std::string>(j_null) == std::nullopt);
+        CHECK_THROWS_WITH(std::optional<std::string>(j_null) == std::nullopt,
+                          "[json.exception.type_error.302] type must be string, but is null");
     }
 
     SECTION("string")
@@ -1746,7 +1747,8 @@ 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);
+        std::vector<std::optional<int>> tmp = j_array;
+        CHECK(tmp == opt_array);
     }
 
     SECTION("object")
@@ -1755,7 +1757,8 @@ TEST_CASE("std::optional")
         std::map<std::string, std::optional<int>> opt_object {{"one", 1}, {"two", 2}, {"zero", std::nullopt}};
 
         CHECK(json(opt_object) == j_object);
-        CHECK(std::map<std::string, std::optional<int>>(j_object) == opt_object);
+        std::map<std::string, std::optional<int>> tmp =j_object;
+        CHECK(tmp == opt_object);
     }
 }
 #endif