diff --git a/server/core/config_runtime.cc b/server/core/config_runtime.cc
index 9a73bd6e2..e3f297564 100644
--- a/server/core/config_runtime.cc
+++ b/server/core/config_runtime.cc
@@ -13,7 +13,7 @@
 
 #include <maxscale/ccdefs.hh>
 
-#include "internal/config_runtime.h"
+#include "internal/config_runtime.hh"
 
 #include <algorithm>
 #include <cinttypes>
diff --git a/server/core/externcmd.cc b/server/core/externcmd.cc
index 2c2dc736f..587606196 100644
--- a/server/core/externcmd.cc
+++ b/server/core/externcmd.cc
@@ -11,7 +11,7 @@
  * Public License.
  */
 
-#include "internal/externcmd.h"
+#include "internal/externcmd.hh"
 
 #include <ctype.h>
 #include <errno.h>
diff --git a/server/core/internal/config_runtime.h b/server/core/internal/config_runtime.hh
similarity index 98%
rename from server/core/internal/config_runtime.h
rename to server/core/internal/config_runtime.hh
index e1f4bc73d..2e85b5d07 100644
--- a/server/core/internal/config_runtime.h
+++ b/server/core/internal/config_runtime.hh
@@ -13,14 +13,14 @@
 #pragma once
 
 /**
- * @file config_runtime.h  - Functions for runtime configuration modifications
+ * @file config_runtime.hh  - Functions for runtime configuration modifications
  */
 
-#include <maxscale/cdefs.h>
+#include <maxscale/ccdefs.hh>
 
 #include <maxscale/adminusers.h>
-#include <maxscale/monitor.h>
-#include <maxscale/server.h>
+#include <maxscale/monitor.hh>
+#include <maxscale/server.hh>
 #include <maxscale/service.hh>
 
 #include "service.hh"
diff --git a/server/core/internal/externcmd.h b/server/core/internal/externcmd.hh
similarity index 98%
rename from server/core/internal/externcmd.h
rename to server/core/internal/externcmd.hh
index a91203e00..fba1195a3 100644
--- a/server/core/internal/externcmd.h
+++ b/server/core/internal/externcmd.hh
@@ -12,14 +12,13 @@
  */
 #pragma once
 
-#include <maxscale/cdefs.h>
-
+#include <maxscale/ccdefs.hh>
 #include <unistd.h>
 
-MXS_BEGIN_DECLS
-
 #define MAXSCALE_EXTCMD_ARG_MAX 256
 
+MXS_BEGIN_DECLS
+
 typedef struct extern_cmd_t
 {
     char** argv;        /**< Argument vector for the command, first being the
diff --git a/server/core/internal/monitor.hh b/server/core/internal/monitor.hh
index 085655c74..607e84ea0 100644
--- a/server/core/internal/monitor.hh
+++ b/server/core/internal/monitor.hh
@@ -18,7 +18,7 @@
 
 #include <maxscale/monitor.hh>
 #include <maxscale/resultset.hh>
-#include "externcmd.h"
+#include "externcmd.hh"
 
 #define MON_ARG_MAX 8192
 
diff --git a/server/core/monitor.cc b/server/core/monitor.cc
index 7cd38130d..cee9c28bf 100644
--- a/server/core/monitor.cc
+++ b/server/core/monitor.cc
@@ -45,7 +45,7 @@
 #include <mysqld_error.h>
 
 #include "internal/config.hh"
-#include "internal/externcmd.h"
+#include "internal/externcmd.hh"
 #include "internal/monitor.hh"
 #include "internal/modules.h"
 
diff --git a/server/core/query_classifier.cc b/server/core/query_classifier.cc
index 3fcfd78a6..93f111cbe 100644
--- a/server/core/query_classifier.cc
+++ b/server/core/query_classifier.cc
@@ -29,7 +29,7 @@
 #include <maxscale/jansson.hh>
 #include <maxscale/buffer.hh>
 
-#include "internal/config_runtime.h"
+#include "internal/config_runtime.hh"
 #include "internal/modules.h"
 #include "internal/trxboundaryparser.hh"
 
diff --git a/server/core/resource.cc b/server/core/resource.cc
index 6b373f149..2b623c8cd 100644
--- a/server/core/resource.cc
+++ b/server/core/resource.cc
@@ -26,7 +26,7 @@
 #include <maxscale/server.hh>
 #include <maxscale/routingworker.hh>
 
-#include "internal/config_runtime.h"
+#include "internal/config_runtime.hh"
 #include "internal/filter.hh"
 #include "internal/httprequest.hh"
 #include "internal/httpresponse.hh"
diff --git a/server/modules/routing/debugcli/debugcmd.cc b/server/modules/routing/debugcli/debugcmd.cc
index 479da8d3a..a7ed96b81 100644
--- a/server/modules/routing/debugcli/debugcmd.cc
+++ b/server/modules/routing/debugcli/debugcmd.cc
@@ -57,7 +57,7 @@
 #include <debugcli.h>
 
 #include "../../../core/internal/config.hh"
-#include "../../../core/internal/config_runtime.h"
+#include "../../../core/internal/config_runtime.hh"
 #include "../../../core/internal/maxscale.h"
 #include "../../../core/internal/modules.h"
 #include "../../../core/internal/monitor.hh"