diff --git a/push/include/prometheus/gateway.h b/push/include/prometheus/gateway.h
index 25e9f1ea..f5c74708 100644
--- a/push/include/prometheus/gateway.h
+++ b/push/include/prometheus/gateway.h
@@ -29,7 +29,7 @@ class PROMETHEUS_CPP_PUSH_EXPORT Gateway {
           const std::string& jobname, const Labels& labels = {},
           const std::string& username = {}, const std::string& password = {},
           std::chrono::seconds timeout = {},
-          std::function<void(CURL*)> presetupCurl = std::nullptr_t);
+          std::function<void(CURL*)> presetupCurl = nullptr);
 
   Gateway(const Gateway&) = delete;
   Gateway(Gateway&&) = delete;
diff --git a/push/src/detail/curl_wrapper.h b/push/src/detail/curl_wrapper.h
index 97d582f4..104463cb 100644
--- a/push/src/detail/curl_wrapper.h
+++ b/push/src/detail/curl_wrapper.h
@@ -13,7 +13,7 @@ class CurlWrapper {
  public:
   CurlWrapper(const std::string& username,
               const std::string& password,
-              std::function<void(CURL*)> presetupCurl = std::nullptr_t);
+              std::function<void(CURL*)> presetupCurl = nullptr);
 
   CurlWrapper(const CurlWrapper&) = delete;
   CurlWrapper(CurlWrapper&&) = delete;