diff --git a/requester/handler.hpp b/requester/handler.hpp
index 1bb9cc4..2af4ade 100644
--- a/requester/handler.hpp
+++ b/requester/handler.hpp
@@ -62,11 +62,6 @@
 
 using ResponseHandler = fu2::unique_function<void(
     mctp_eid_t eid, const pldm_msg* response, size_t respMsgLen)>;
-using namespace std::chrono;
-using namespace sdeventplus;
-using namespace sdeventplus::source;
-using namespace pldm::dbus_api;
-using namespace phosphor;
 
 /** @class Handler
  *
@@ -101,11 +96,12 @@
      *  @param[in] responseTimeOut - time to wait between each retry
      */
     explicit Handler(
-        int fd, Event& event, Requester& requester,
-        seconds instanceIdExpiryInterval =
-            seconds(INSTANCE_ID_EXPIRATION_INTERVAL),
+        int fd, sdeventplus::Event& event, pldm::dbus_api::Requester& requester,
+        std::chrono::seconds instanceIdExpiryInterval =
+            std::chrono::seconds(INSTANCE_ID_EXPIRATION_INTERVAL),
         uint8_t numRetries = static_cast<uint8_t>(NUMBER_OF_REQUEST_RETRIES),
-        milliseconds responseTimeOut = milliseconds(RESPONSE_TIME_OUT)) :
+        std::chrono::milliseconds responseTimeOut =
+            std::chrono::milliseconds(RESPONSE_TIME_OUT)) :
         fd(fd),
         event(event), requester(requester),
         instanceIdExpiryInterval(instanceIdExpiryInterval),
@@ -181,7 +177,8 @@
 
         try
         {
-            timer->start(duration_cast<microseconds>(instanceIdExpiryInterval));
+            timer->start(duration_cast<std::chrono::microseconds>(
+                instanceIdExpiryInterval));
         }
         catch (const std::runtime_error& e)
         {
@@ -237,19 +234,22 @@
     }
 
   private:
-    int fd;               //!< file descriptor of MCTP communications socket
-    Event& event;         //!< reference to PLDM daemon's main event loop
-    Requester& requester; //!< reference to Requester object
-    seconds instanceIdExpiryInterval; //!< Instance ID expiration interval
-    uint8_t numRetries;               //!< number of request retries
-    milliseconds responseTimeOut;     //!< time to wait between each retry
+    int fd; //!< file descriptor of MCTP communications socket
+    sdeventplus::Event& event; //!< reference to PLDM daemon's main event loop
+    pldm::dbus_api::Requester& requester; //!< reference to Requester object
+    std::chrono::seconds
+        instanceIdExpiryInterval; //!< Instance ID expiration interval
+    uint8_t numRetries;           //!< number of request retries
+    std::chrono::milliseconds
+        responseTimeOut; //!< time to wait between each retry
 
     /** @brief Container for storing the details of the PLDM request message,
      *         handler for the corresponding PLDM response and the timer object
      *         for the Instance ID expiration
      */
-    using RequestValue = std::tuple<std::unique_ptr<RequestInterface>,
-                                    ResponseHandler, std::unique_ptr<Timer>>;
+    using RequestValue =
+        std::tuple<std::unique_ptr<RequestInterface>, ResponseHandler,
+                   std::unique_ptr<phosphor::Timer>>;
 
     /** @brief Container for storing the PLDM request entries */
     std::unordered_map<RequestKey, RequestValue, RequestKeyHasher> handlers;
@@ -257,7 +257,8 @@
     /** @brief Container to store information about the request entries to be
      *         removed after the instance ID timer expires
      */
-    std::unordered_map<RequestKey, std::unique_ptr<Defer>, RequestKeyHasher>
+    std::unordered_map<RequestKey, std::unique_ptr<sdeventplus::source::Defer>,
+                       RequestKeyHasher>
         removeRequestContainer;
 
     /** @brief Remove request entry for which the instance ID expired
diff --git a/requester/request.hpp b/requester/request.hpp
index 6bb016d..f1a91d7 100644
--- a/requester/request.hpp
+++ b/requester/request.hpp
@@ -18,8 +18,6 @@
 namespace requester
 {
 
-using namespace std::chrono;
-
 /** @class RequestRetryTimer
  *
  *  The abstract base class for implementing the PLDM request retry logic. This
@@ -44,7 +42,7 @@
      *  @param[in] timeout - time to wait between each retry in milliseconds
      */
     explicit RequestRetryTimer(sdeventplus::Event& event, uint8_t numRetries,
-                               milliseconds timeout) :
+                               std::chrono::milliseconds timeout) :
 
         event(event),
         numRetries(numRetries), timeout(timeout),
@@ -67,7 +65,8 @@
         {
             if (numRetries)
             {
-                timer.start(duration_cast<microseconds>(timeout), true);
+                timer.start(duration_cast<std::chrono::microseconds>(timeout),
+                            true);
             }
         }
         catch (const std::runtime_error& e)
@@ -94,7 +93,8 @@
   protected:
     sdeventplus::Event& event; //!< reference to PLDM daemon's main event loop
     uint8_t numRetries;        //!< number of request retries
-    milliseconds timeout;  //!< time to wait between each retry in milliseconds
+    std::chrono::milliseconds
+        timeout;           //!< time to wait between each retry in milliseconds
     phosphor::Timer timer; //!< manages starting timers and handling timeouts
 
     /** @brief Sends the PLDM request message
@@ -147,7 +147,7 @@
      */
     explicit Request(int fd, mctp_eid_t eid, sdeventplus::Event& event,
                      pldm::Request&& requestMsg, uint8_t numRetries,
-                     milliseconds timeout) :
+                     std::chrono::milliseconds timeout) :
         RequestRetryTimer(event, numRetries, timeout),
         fd(fd), eid(eid), requestMsg(std::move(requestMsg))
     {}
diff --git a/requester/test/mock_request.hpp b/requester/test/mock_request.hpp
index b8e9efb..8b51a03 100644
--- a/requester/test/mock_request.hpp
+++ b/requester/test/mock_request.hpp
@@ -11,14 +11,12 @@
 namespace requester
 {
 
-using namespace std::chrono;
-
 class MockRequest : public RequestRetryTimer
 {
   public:
     MockRequest(int /*fd*/, mctp_eid_t /*eid*/, sdeventplus::Event& event,
                 pldm::Request&& /*requestMsg*/, uint8_t numRetries,
-                milliseconds responseTimeOut) :
+                std::chrono::milliseconds responseTimeOut) :
         RequestRetryTimer(event, numRetries, responseTimeOut)
     {}