diff --git a/server/core/internal/secrets.h b/server/core/internal/secrets.hh
similarity index 100%
rename from server/core/internal/secrets.h
rename to server/core/internal/secrets.hh
diff --git a/server/core/maxkeys.cc b/server/core/maxkeys.cc
index 3c0fa5f0a..f45a6b20d 100644
--- a/server/core/maxkeys.cc
+++ b/server/core/maxkeys.cc
@@ -19,7 +19,7 @@
 #include <stdio.h>
 #include <maxscale/paths.h>
 #include <maxscale/random.h>
-#include "internal/secrets.h"
+#include "internal/secrets.hh"
 
 #ifdef HAVE_GLIBC
 struct option options[] =
diff --git a/server/core/maxpasswd.cc b/server/core/maxpasswd.cc
index efc5f7191..3311db7bc 100644
--- a/server/core/maxpasswd.cc
+++ b/server/core/maxpasswd.cc
@@ -26,7 +26,7 @@
 #include <maxscale/random.h>
 #include <maxscale/alloc.h>
 
-#include "internal/secrets.h"
+#include "internal/secrets.hh"
 
 #ifdef HAVE_GLIBC
 struct option options[] =
diff --git a/server/core/secrets.cc b/server/core/secrets.cc
index a9a04502c..3144c13e6 100644
--- a/server/core/secrets.cc
+++ b/server/core/secrets.cc
@@ -24,7 +24,7 @@
 #include <maxscale/random.h>
 #include <maxscale/utils.h>
 
-#include "internal/secrets.h"
+#include "internal/secrets.hh"
 
 /**
  * Generate a random printable character
diff --git a/server/core/test/test_dcb.cc b/server/core/test/test_dcb.cc
index 1da99a2f2..45c5a2415 100644
--- a/server/core/test/test_dcb.cc
+++ b/server/core/test/test_dcb.cc
@@ -39,7 +39,7 @@
 #include <maxscale/routingworker.hh>
 
 #include "../dcb.cc"
-#include "test_utils.h"
+#include "test_utils.hh"
 
 /**
  * test1    Allocate a dcb and do lots of other things
diff --git a/server/core/test/test_poll.cc b/server/core/test/test_poll.cc
index 5d43cb476..71deb55b6 100644
--- a/server/core/test/test_poll.cc
+++ b/server/core/test/test_poll.cc
@@ -37,7 +37,7 @@
 #include <maxscale/listener.hh>
 #include <maxscale/service.hh>
 
-#include "test_utils.h"
+#include "test_utils.hh"
 #include "../internal/service.hh"
 #include "../internal/session.hh"
 
diff --git a/server/core/test/test_service.cc b/server/core/test/test_service.cc
index d05d94c0b..be32f16b9 100644
--- a/server/core/test/test_service.cc
+++ b/server/core/test/test_service.cc
@@ -37,7 +37,7 @@
 #include <maxscale/alloc.h>
 
 #include "../internal/service.hh"
-#include "test_utils.h"
+#include "test_utils.hh"
 #include "../config.cc"
 
 /**
diff --git a/server/core/test/test_utils.h b/server/core/test/test_utils.hh
similarity index 96%
rename from server/core/test/test_utils.h
rename to server/core/test/test_utils.hh
index ceb0cad18..e07e7338f 100644
--- a/server/core/test/test_utils.h
+++ b/server/core/test/test_utils.hh
@@ -1,6 +1,4 @@
 #pragma once
-#ifndef TEST_UTILS_H
-#define TEST_UTILS_H
 /*
  * Copyright (c) 2016 MariaDB Corporation Ab
  *
@@ -14,7 +12,7 @@
  * Public License.
  */
 
-#include <maxscale/cdefs.h>
+#include <maxscale/ccdefs.hh>
 #include <maxbase/maxbase.hh>
 #include <maxscale/dcb.hh>
 #include <maxscale/housekeeper.h>
@@ -66,5 +64,3 @@ void init_test_env(char* __attribute((unused)) path = nullptr, uint32_t init_typ
     preload_module("readconnroute", "server/modules/routing/readconnroute/", MODULE_ROUTER);
     preload_module("mysqlauth", "/server/modules/authenticator/MySQLAuth/", MODULE_AUTHENTICATOR);
 }
-
-#endif
diff --git a/server/modules/filter/cache/test/test_cacheoptions.cc b/server/modules/filter/cache/test/test_cacheoptions.cc
index 200a0057e..93ef34ca5 100644
--- a/server/modules/filter/cache/test/test_cacheoptions.cc
+++ b/server/modules/filter/cache/test/test_cacheoptions.cc
@@ -20,7 +20,7 @@
 #include <maxscale/mock/session.hh>
 #include "../cachefilter.hh"
 
-#include "../../../../core/test/test_utils.h"
+#include "../../../../core/test/test_utils.hh"
 
 using namespace std;
 using maxscale::FilterModule;
diff --git a/server/modules/filter/dbfwfilter/test/test_dbfwfilter.cc b/server/modules/filter/dbfwfilter/test/test_dbfwfilter.cc
index 7c2c8c44a..19e63bcba 100644
--- a/server/modules/filter/dbfwfilter/test/test_dbfwfilter.cc
+++ b/server/modules/filter/dbfwfilter/test/test_dbfwfilter.cc
@@ -22,7 +22,7 @@
 #include <maxscale/mock/client.hh>
 #include "tempfile.hh"
 
-#include "../../../../core/test/test_utils.h"
+#include "../../../../core/test/test_utils.hh"
 
 using namespace std;
 using maxscale::FilterModule;
diff --git a/server/modules/routing/maxinfo/maxinfo.cc b/server/modules/routing/maxinfo/maxinfo.cc
index 03d311071..4a9e3fe74 100644
--- a/server/modules/routing/maxinfo/maxinfo.cc
+++ b/server/modules/routing/maxinfo/maxinfo.cc
@@ -26,7 +26,7 @@
  * @endverbatim
  */
 
-#include "maxinfo.h"
+#include "maxinfo.hh"
 
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/server/modules/routing/maxinfo/maxinfo.h b/server/modules/routing/maxinfo/maxinfo.hh
similarity index 100%
rename from server/modules/routing/maxinfo/maxinfo.h
rename to server/modules/routing/maxinfo/maxinfo.hh
diff --git a/server/modules/routing/maxinfo/maxinfo_error.cc b/server/modules/routing/maxinfo/maxinfo_error.cc
index 765bd0658..27ce0f4b4 100644
--- a/server/modules/routing/maxinfo/maxinfo_error.cc
+++ b/server/modules/routing/maxinfo/maxinfo_error.cc
@@ -23,7 +23,7 @@
  * @endverbatim
  */
 
-#include "maxinfo.h"
+#include "maxinfo.hh"
 
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/server/modules/routing/maxinfo/maxinfo_exec.cc b/server/modules/routing/maxinfo/maxinfo_exec.cc
index 8147c3a54..2f719e86f 100644
--- a/server/modules/routing/maxinfo/maxinfo_exec.cc
+++ b/server/modules/routing/maxinfo/maxinfo_exec.cc
@@ -24,7 +24,7 @@
  * @endverbatim
  */
 
-#include "maxinfo.h"
+#include "maxinfo.hh"
 
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/server/modules/routing/maxinfo/maxinfo_parse.cc b/server/modules/routing/maxinfo/maxinfo_parse.cc
index 572bfefbe..ca6aa4662 100644
--- a/server/modules/routing/maxinfo/maxinfo_parse.cc
+++ b/server/modules/routing/maxinfo/maxinfo_parse.cc
@@ -24,7 +24,7 @@
  * @endverbatim
  */
 
-#include "maxinfo.h"
+#include "maxinfo.hh"
 
 #include <ctype.h>
 #include <stdio.h>