diff --git a/src/crow_getroutes_test.cpp b/src/crow_getroutes_test.cpp
index 20c14ea..eea045c 100644
--- a/src/crow_getroutes_test.cpp
+++ b/src/crow_getroutes_test.cpp
@@ -1,4 +1,4 @@
-#include <app.h>
+#include <app.hpp>
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
@@ -44,4 +44,4 @@
                                      testing::Pointee(std::string("/baz")),
                                      testing::Pointee(std::string("/boo")),
                                      testing::Pointee(std::string("/moo"))));
-}
\ No newline at end of file
+}
diff --git a/src/security_headers_middleware_test.cpp b/src/security_headers_middleware_test.cpp
index 500839a..f5cd3d5 100644
--- a/src/security_headers_middleware_test.cpp
+++ b/src/security_headers_middleware_test.cpp
@@ -1,5 +1,4 @@
-#include <app.h>
-
+#include <app.hpp>
 #include <security_headers_middleware.hpp>
 
 #include <gmock/gmock.h>
diff --git a/src/webassets_test.cpp b/src/webassets_test.cpp
index 48dc398..b182f46 100644
--- a/src/webassets_test.cpp
+++ b/src/webassets_test.cpp
@@ -1,5 +1,4 @@
-#include <app.h>
-
+#include <app.hpp>
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/lexical_cast.hpp>
 #include <gzip_helper.hpp>
diff --git a/src/webserver_main.cpp b/src/webserver_main.cpp
index cd31152..3e796c2 100644
--- a/src/webserver_main.cpp
+++ b/src/webserver_main.cpp
@@ -1,6 +1,6 @@
-#include <app.h>
 #include <systemd/sd-daemon.h>
 
+#include <app.hpp>
 #include <boost/asio/io_context.hpp>
 #include <dbus_monitor.hpp>
 #include <dbus_singleton.hpp>