diff --git a/redfish-core/include/error_messages.hpp b/redfish-core/include/error_messages.hpp
index 1a5b941..76052fc 100644
--- a/redfish-core/include/error_messages.hpp
+++ b/redfish-core/include/error_messages.hpp
@@ -14,13 +14,19 @@
 // limitations under the License.
 */
 #pragma once
+
 #include "http_response.hpp"
+#include "source_location.hpp"
 
 #include <boost/url/url_view.hpp>
 #include <nlohmann/json.hpp>
-#include <source_location.hpp>
 
+#include <cstdint>
 #include <string>
+#include <string_view>
+
+// IWYU pragma: no_include <cstdint.h>
+// IWYU pragma: no_forward_declare crow::Response
 
 namespace redfish
 {
diff --git a/redfish-core/src/error_messages.cpp b/redfish-core/src/error_messages.cpp
index 654353d..c6d27a9 100644
--- a/redfish-core/src/error_messages.cpp
+++ b/redfish-core/src/error_messages.cpp
@@ -13,16 +13,25 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 */
-#include "http_response.hpp"
-#include "registries/base_message_registry.hpp"
+#include "error_messages.hpp"
 
+#include "http_response.hpp"
+#include "logging.hpp"
+#include "nlohmann/json.hpp"
+#include "registries.hpp"
+#include "registries/base_message_registry.hpp"
+#include "source_location.hpp"
+
+#include <boost/beast/http/field.hpp>
 #include <boost/beast/http/status.hpp>
-#include <boost/url/url.hpp>
-#include <error_messages.hpp>
-#include <logging.hpp>
-#include <nlohmann/json.hpp>
 
 #include <array>
+#include <cstddef>
+#include <span>
+#include <string>
+#include <utility>
+
+// IWYU pragma: no_include <stddef.h>
 
 namespace redfish
 {