diff --git a/untests/CMakeLists.txt b/untests/CMakeLists.txt
index f2c526a..d6d767d 100644
--- a/untests/CMakeLists.txt
+++ b/untests/CMakeLists.txt
@@ -64,3 +64,19 @@ if(NOT tencent_rapidjson_POPULATED)
     target_include_directories(${PROJECT_NAME}
         PRIVATE ${tencent_rapidjson_SOURCE_DIR}/include)
 endif()
+
+#
+# blackmatov/promise.hpp
+#
+
+include(FetchContent)
+FetchContent_Declare(
+    blackmatov_promise_hpp
+    GIT_REPOSITORY https://github.com/blackmatov/promise.hpp)
+
+FetchContent_GetProperties(blackmatov_promise_hpp)
+if(NOT blackmatov_promise_hpp_POPULATED)
+    FetchContent_Populate(blackmatov_promise_hpp)
+    target_include_directories(${PROJECT_NAME}
+        PRIVATE ${blackmatov_promise_hpp_SOURCE_DIR}/headers)
+endif()
diff --git a/untests/curly_tests.cpp b/untests/curly_tests.cpp
index c957159..dad6559 100644
--- a/untests/curly_tests.cpp
+++ b/untests/curly_tests.cpp
@@ -16,6 +16,9 @@ namespace json = rapidjson;
 #include <curly.hpp/curly.hpp>
 namespace net = curly_hpp;
 
+#include <promise.hpp/promise.hpp>
+namespace netex = promise_hpp;
+
 #include "png_data.h"
 #include "jpeg_data.h"