diff --git a/gnucash/gnome/assistant-loan.cpp b/gnucash/gnome/assistant-loan.cpp
index 943ab3c244f..54578c17c3c 100644
--- a/gnucash/gnome/assistant-loan.cpp
+++ b/gnucash/gnome/assistant-loan.cpp
@@ -34,7 +34,7 @@
 #include "assistant-loan.h"
 #include "SchedXaction.h"
 #include "SX-book.h"
-#include "SX-ttinfo.h"
+#include "SX-ttinfo.hpp"
 #include "gnc-amount-edit.h"
 #include "gnc-account-sel.h"
 #include "gnc-date.h"
diff --git a/gnucash/gnome/dialog-sx-from-trans.cpp b/gnucash/gnome/dialog-sx-from-trans.cpp
index 4fc436f4964..5aa4de3e681 100644
--- a/gnucash/gnome/dialog-sx-from-trans.cpp
+++ b/gnucash/gnome/dialog-sx-from-trans.cpp
@@ -43,7 +43,7 @@
 #include "Recurrence.h"
 #include "SchedXaction.h"
 #include "SX-book.h"
-#include "SX-ttinfo.h"
+#include "SX-ttinfo.hpp"
 #include <glib/gi18n.h>
 #include <gtk/gtk.h>
 #include <stdlib.h>
diff --git a/libgnucash/app-utils/test/test-sx.cpp b/libgnucash/app-utils/test/test-sx.cpp
index 163a38e06cf..d8a3c18a7f6 100644
--- a/libgnucash/app-utils/test/test-sx.cpp
+++ b/libgnucash/app-utils/test/test-sx.cpp
@@ -24,7 +24,7 @@
 
 #include <stdlib.h>
 #include "SX-book.h"
-#include "SX-ttinfo.h"
+#include "SX-ttinfo.hpp"
 #include "gnc-date.h"
 #include "gnc-session.h"
 #include "gnc-sx-instance-model.h"
diff --git a/libgnucash/engine/CMakeLists.txt b/libgnucash/engine/CMakeLists.txt
index 2058b5866bc..7fa07271f6a 100644
--- a/libgnucash/engine/CMakeLists.txt
+++ b/libgnucash/engine/CMakeLists.txt
@@ -8,7 +8,7 @@ set(engine_noinst_HEADERS
   AccountP.hpp
   SplitP.hpp
   SX-book.h
-  SX-ttinfo.h
+  SX-ttinfo.hpp
   TransactionP.hpp
   gnc-backend-prov.hpp
   gnc-date-p.h
@@ -37,7 +37,7 @@ set (engine_HEADERS
   Recurrence.h
   SchedXaction.h
   SX-book.h
-  SX-ttinfo.h
+  SX-ttinfo.hpp
   Query.h
   Scrub.h
   Scrub2.h
diff --git a/libgnucash/engine/SX-ttinfo.cpp b/libgnucash/engine/SX-ttinfo.cpp
index e14482d0199..3d1ffd72933 100644
--- a/libgnucash/engine/SX-ttinfo.cpp
+++ b/libgnucash/engine/SX-ttinfo.cpp
@@ -25,7 +25,7 @@
 
 #include <config.h>
 
-#include "SX-ttinfo.h"
+#include "SX-ttinfo.hpp"
 
 struct TTInfo_s
 {
diff --git a/libgnucash/engine/SX-ttinfo.h b/libgnucash/engine/SX-ttinfo.hpp
similarity index 98%
rename from libgnucash/engine/SX-ttinfo.h
rename to libgnucash/engine/SX-ttinfo.hpp
index 1c36d1d3ea6..72486f7a662 100644
--- a/libgnucash/engine/SX-ttinfo.h
+++ b/libgnucash/engine/SX-ttinfo.hpp
@@ -31,10 +31,6 @@
 #include "Account.h"
 #include "gnc-commodity.h"
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 typedef struct TTInfo_s TTInfo;
 typedef struct TTSplitInfo_s TTSplitInfo;
 
@@ -91,8 +87,4 @@ const char *gnc_ttsplitinfo_get_debit_formula(TTSplitInfo *split_i);
 void gnc_ttsplitinfo_set_account(TTSplitInfo *split_i, Account *acc);
 Account *gnc_ttsplitinfo_get_account(TTSplitInfo *split_i);
 
-#ifdef __cplusplus
-}
-#endif
-
 #endif
diff --git a/libgnucash/engine/SchedXaction.cpp b/libgnucash/engine/SchedXaction.cpp
index 403f7f24413..293b173f7a6 100644
--- a/libgnucash/engine/SchedXaction.cpp
+++ b/libgnucash/engine/SchedXaction.cpp
@@ -34,7 +34,7 @@
 #include "Account.hpp"
 #include "SX-book.h"
 #include "SX-book-p.h"
-#include "SX-ttinfo.h"
+#include "SX-ttinfo.hpp"
 #include "SchedXaction.h"
 #include "Transaction.h"
 #include "gnc-engine.h"