diff --git a/po/POTFILES.in b/po/POTFILES.in
index af02822487..58c75b9665 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -58,7 +58,7 @@ src/backend/sql/gnc-owner-sql.c
 src/backend/sql/gnc-price-sql.c
 src/backend/sql/gnc-recurrence-sql.c
 src/backend/sql/gnc-schedxaction-sql.c
-src/backend/sql/gnc-slots-sql.c
+src/backend/sql/gnc-slots-sql.cpp
 src/backend/sql/gnc-tax-table-sql.c
 src/backend/sql/gnc-transaction-sql.c
 src/backend/sql/gnc-vendor-sql.c
@@ -91,8 +91,8 @@ src/backend/xml/io-gncxml-v1.c
 src/backend/xml/io-gncxml-v2.c
 src/backend/xml/io-utils.c
 src/backend/xml/sixtp.c
-src/backend/xml/sixtp-dom-generators.c
-src/backend/xml/sixtp-dom-parsers.c
+src/backend/xml/sixtp-dom-generators.cpp
+src/backend/xml/sixtp-dom-parsers.cpp
 src/backend/xml/sixtp-stack.c
 src/backend/xml/sixtp-to-dom-parser.c
 src/backend/xml/sixtp-utils.c
diff --git a/src/backend/sql/Makefile.am b/src/backend/sql/Makefile.am
index d656030511..11a7bd5af3 100644
--- a/src/backend/sql/Makefile.am
+++ b/src/backend/sql/Makefile.am
@@ -38,7 +38,7 @@ libgnc_backend_sql_la_SOURCES = \
   gnc-price-sql.c \
   gnc-recurrence-sql.c \
   gnc-schedxaction-sql.c \
-  gnc-slots-sql.c \
+  gnc-slots-sql.cpp \
   gnc-tax-table-sql.c \
   gnc-transaction-sql.c \
   gnc-vendor-sql.c \
diff --git a/src/backend/sql/gnc-slots-sql.c b/src/backend/sql/gnc-slots-sql.cpp
similarity index 97%
rename from src/backend/sql/gnc-slots-sql.c
rename to src/backend/sql/gnc-slots-sql.cpp
index 0611e3e7f9..9bd6b5c085 100644
--- a/src/backend/sql/gnc-slots-sql.c
+++ b/src/backend/sql/gnc-slots-sql.cpp
@@ -25,7 +25,8 @@
  * This file implements the top-level QofBackend API for saving/
  * restoring data to/from an SQL db
  */
-
+extern "C"
+{
 #include "config.h"
 
 #include <glib.h>
@@ -40,7 +41,7 @@
 #ifdef S_SPLINT_S
 #include "splint-defs.h"
 #endif
-
+}
 /*@ unused @*/ static QofLogModule log_module = G_LOG_DOMAIN;
 
 #define TABLE_NAME "slots"
@@ -323,7 +324,7 @@ get_slot_type( gpointer pObject )
 {
     slot_info_t* pInfo = (slot_info_t*)pObject;
 
-    g_return_val_if_fail( pObject != NULL, 0 );
+    g_return_val_if_fail( pObject != NULL, KVP_TYPE_INVALID );
 
 //    return (gpointer)kvp_value_get_type( pInfo->pKvpValue );
     return pInfo->value_type;
@@ -337,7 +338,7 @@ set_slot_type( gpointer pObject, /*@ null @*/ gpointer pValue )
     g_return_if_fail( pObject != NULL );
     g_return_if_fail( pValue != NULL );
 
-    pInfo->value_type = (KvpValueType)pValue;
+    pInfo->value_type = static_cast<KvpValueType>(GPOINTER_TO_INT(pValue));
 }
 
 static gint64
@@ -709,7 +710,8 @@ save_slot( const gchar* key, KvpValue* value, gpointer data )
 gboolean
 gnc_sql_slots_save( GncSqlBackend* be, const GncGUID* guid, gboolean is_infant, KvpFrame* pFrame )
 {
-    slot_info_t slot_info = { NULL, NULL, TRUE, NULL, 0, NULL, FRAME, NULL, g_string_new(NULL) };
+     slot_info_t slot_info = { NULL, NULL, TRUE, NULL, KVP_TYPE_INVALID, NULL, FRAME, NULL, g_string_new(NULL) };
+     KvpFrame *pFrame = qof_instance_get_slots (inst);
 
     g_return_val_if_fail( be != NULL, FALSE );
     g_return_val_if_fail( guid != NULL, FALSE );
@@ -736,7 +738,7 @@ gnc_sql_slots_delete( GncSqlBackend* be, const GncGUID* guid )
     GncSqlResult* result;
     gchar guid_buf[GUID_ENCODING_LENGTH + 1];
     GncSqlStatement* stmt;
-    slot_info_t slot_info = { NULL, NULL, TRUE, NULL, 0, NULL, FRAME, NULL, g_string_new(NULL) };
+    slot_info_t slot_info = { NULL, NULL, TRUE, NULL, KVP_TYPE_INVALID, NULL, FRAME, NULL, g_string_new(NULL) };
 
     g_return_val_if_fail( be != NULL, FALSE );
     g_return_val_if_fail( guid != NULL, FALSE );
@@ -818,7 +820,7 @@ load_slot( slot_info_t *pInfo, GncSqlRow* row )
 void
 gnc_sql_slots_load( GncSqlBackend* be, QofInstance* inst )
 {
-    slot_info_t info = { NULL, NULL, TRUE, NULL, 0, NULL, FRAME, NULL, g_string_new(NULL) };
+    slot_info_t info = { NULL, NULL, TRUE, NULL, KVP_TYPE_INVALID, NULL, FRAME, NULL, g_string_new(NULL) };
     g_return_if_fail( be != NULL );
     g_return_if_fail( inst != NULL );
 
@@ -883,7 +885,7 @@ load_obj_guid( const GncSqlBackend* be, GncSqlRow* row )
 static void
 load_slot_for_list_item( GncSqlBackend* be, GncSqlRow* row, QofCollection* coll )
 {
-    slot_info_t slot_info = { NULL, NULL, TRUE, NULL, 0, NULL, FRAME, NULL, NULL };
+    slot_info_t slot_info = { NULL, NULL, TRUE, NULL, KVP_TYPE_INVALID, NULL, FRAME, NULL, NULL };
     const GncGUID* guid;
     QofInstance* inst;
 
@@ -969,7 +971,7 @@ gnc_sql_slots_load_for_list( GncSqlBackend* be, GList* list )
 static void
 load_slot_for_book_object( GncSqlBackend* be, GncSqlRow* row, BookLookupFn lookup_fn )
 {
-    slot_info_t slot_info = { NULL, NULL, TRUE, NULL, 0, NULL, FRAME, NULL, NULL };
+    slot_info_t slot_info = { NULL, NULL, TRUE, NULL, KVP_TYPE_INVALID, NULL, FRAME, NULL, NULL };
     const GncGUID* guid;
     QofInstance* inst;
 
diff --git a/src/backend/sql/gnc-slots-sql.h b/src/backend/sql/gnc-slots-sql.h
index e7f00eb678..a9d6685d3c 100644
--- a/src/backend/sql/gnc-slots-sql.h
+++ b/src/backend/sql/gnc-slots-sql.h
@@ -28,6 +28,10 @@
 
 #ifndef GNC_SLOTS_SQL_H
 #define GNC_SLOTS_SQL_H
+#ifdef __cplusplus
+extern "C"
+{
+#endif
 
 #include <glib.h>
 #include "guid.h"
@@ -88,4 +92,7 @@ void gnc_sql_slots_load_for_sql_subquery( GncSqlBackend* be, const gchar* subque
 
 void gnc_sql_init_slots_handler( void );
 
+#ifdef __cplusplus
+}
+#endif
 #endif /* GNC_SLOTS_SQL_H */
diff --git a/src/backend/xml/Makefile.am b/src/backend/xml/Makefile.am
index 7709aa1709..e7bb12e610 100644
--- a/src/backend/xml/Makefile.am
+++ b/src/backend/xml/Makefile.am
@@ -45,8 +45,8 @@ libgnc_backend_xml_utils_la_SOURCES = \
   io-gncxml-v1.c \
   io-gncxml-v2.c \
   io-utils.c \
-  sixtp-dom-generators.c \
-  sixtp-dom-parsers.c \
+  sixtp-dom-generators.cpp \
+  sixtp-dom-parsers.cpp \
   sixtp-stack.c \
   sixtp-to-dom-parser.c \
   sixtp-utils.c \
diff --git a/src/backend/xml/sixtp-dom-generators.c b/src/backend/xml/sixtp-dom-generators.cpp
similarity index 97%
rename from src/backend/xml/sixtp-dom-generators.c
rename to src/backend/xml/sixtp-dom-generators.cpp
index 083bb723c9..665aebddaf 100644
--- a/src/backend/xml/sixtp-dom-generators.c
+++ b/src/backend/xml/sixtp-dom-generators.cpp
@@ -20,7 +20,8 @@
  * Boston, MA  02110-1301,  USA       gnu@gnu.org                   *
  *                                                                  *
  ********************************************************************/
-
+extern "C"
+{
 #define __EXTENSIONS__
 
 #include "config.h"
@@ -31,6 +32,7 @@
 
 #include "sixtp-dom-generators.h"
 #include "sixtp-utils.h"
+}
 
 static QofLogModule log_module = GNC_MOD_IO;
 
@@ -237,11 +239,11 @@ double_to_string(double value)
 }
 
 static void
-add_text_to_node(xmlNodePtr node, gchar *type, gchar *val)
+add_text_to_node(xmlNodePtr node, const gchar *type, gchar *val)
 {
     gchar *newtype = g_strdup (type);
     gchar *newval = g_strdup (val);
-    xmlSetProp(node, BAD_CAST "type", checked_char_cast (type));
+    xmlSetProp(node, BAD_CAST "type", BAD_CAST type);
     xmlNodeSetContent(node, checked_char_cast (val));
     g_free (newtype);
     g_free(newval);
@@ -251,7 +253,7 @@ static void
 add_kvp_slot(const char * key, KvpValue* value, xmlNodePtr node);
 
 static void
-add_kvp_value_node(xmlNodePtr node, gchar *tag, KvpValue* val)
+add_kvp_value_node(xmlNodePtr node, const gchar *tag, KvpValue* val)
 {
     xmlNodePtr val_node;
     kvp_value_t kvp_type;
diff --git a/src/backend/xml/sixtp-dom-generators.h b/src/backend/xml/sixtp-dom-generators.h
index 9a8b3b71cf..09b14b5b7c 100644
--- a/src/backend/xml/sixtp-dom-generators.h
+++ b/src/backend/xml/sixtp-dom-generators.h
@@ -24,6 +24,10 @@
 #ifndef SIXTP_DOM_GENERATORS_H
 #define SIXTP_DOM_GENERATORS_H
 
+#ifdef __cplusplus
+extern "C"
+{
+#endif
 #include <glib.h>
 
 #include "gnc-xml-helper.h"
@@ -49,4 +53,7 @@ xmlNodePtr recurrence_to_dom_tree(const gchar *tag, const Recurrence *r);
 
 gchar* double_to_string(double value);
 
+#ifdef __cplusplus
+}
+#endif
 #endif /* _SIXTP_DOM_GENERATORS_H_ */
diff --git a/src/backend/xml/sixtp-dom-parsers.c b/src/backend/xml/sixtp-dom-parsers.cpp
similarity index 99%
rename from src/backend/xml/sixtp-dom-parsers.c
rename to src/backend/xml/sixtp-dom-parsers.cpp
index 1eb9c03bb3..aa001655b2 100644
--- a/src/backend/xml/sixtp-dom-parsers.c
+++ b/src/backend/xml/sixtp-dom-parsers.cpp
@@ -20,7 +20,8 @@
  * Boston, MA  02110-1301,  USA       gnu@gnu.org                   *
  *                                                                  *
  ********************************************************************/
-
+extern "C"
+{
 #include "config.h"
 
 #include <glib.h>
@@ -30,7 +31,7 @@
 #include "gnc-engine.h"
 #include "sixtp-utils.h"
 #include "sixtp-dom-parsers.h"
-
+}
 static QofLogModule log_module = GNC_MOD_IO;
 
 GncGUID*
@@ -350,7 +351,7 @@ dom_tree_to_frame_kvp_value(xmlNodePtr node)
 
 struct kvp_val_converter
 {
-    gchar *tag;
+    const gchar *tag;
     KvpValue* (*converter)(xmlNodePtr node);
 };
 
@@ -683,7 +684,8 @@ dom_tree_to_gdate(xmlNodePtr node)
                     }
                     g_free(content);
                     seen_date = TRUE;
-                    g_date_set_dmy( ret, day, month, year );
+                    g_date_set_dmy( ret, day, static_cast<GDateMonth>(month),
+                                    year );
                     if ( !g_date_valid( ret ) )
                     {
                         PWARN("invalid date");
diff --git a/src/backend/xml/sixtp-dom-parsers.h b/src/backend/xml/sixtp-dom-parsers.h
index b48f8b5fcd..efae18ae2f 100644
--- a/src/backend/xml/sixtp-dom-parsers.h
+++ b/src/backend/xml/sixtp-dom-parsers.h
@@ -23,6 +23,10 @@
 
 #ifndef SIXTP_DOM_PARSERS_H
 #define SIXTP_DOM_PARSERS_H
+#ifdef __cplusplus
+extern "C"
+{
+#endif
 
 #include <glib.h>
 
@@ -88,5 +92,7 @@ gboolean dom_tree_generic_parse(xmlNodePtr node,
                                 struct dom_tree_handler *handlers,
                                 gpointer data);
 
-
+#ifdef __cplusplus
+}
+#endif
 #endif /* _SIXTP_DOM_PARSERS_H_ */
diff --git a/src/backend/xml/test/Makefile.am b/src/backend/xml/test/Makefile.am
index d3993533d2..40c10489ec 100644
--- a/src/backend/xml/test/Makefile.am
+++ b/src/backend/xml/test/Makefile.am
@@ -2,8 +2,8 @@
 SUBDIRS = test-files
 
 test_date_converting_SOURCES = \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.c \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.c \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.cpp \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.cpp \
   ${top_srcdir}/src/backend/xml/sixtp-utils.c \
   ${top_srcdir}/src/backend/xml/sixtp.c \
   ${top_srcdir}/src/backend/xml/sixtp-stack.c \
@@ -12,8 +12,8 @@ test_date_converting_SOURCES = \
   test-date-converting.c
 
 test_dom_converters1_SOURCES = \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.c \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.c \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.cpp \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.cpp \
   ${top_srcdir}/src/backend/xml/sixtp-utils.c \
   ${top_srcdir}/src/backend/xml/sixtp.c \
   ${top_srcdir}/src/backend/xml/sixtp-stack.c \
@@ -22,8 +22,8 @@ test_dom_converters1_SOURCES = \
   test-dom-converters1.c
 
 test_kvp_frames_SOURCES = \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.c \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.c \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.cpp \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.cpp \
   ${top_srcdir}/src/backend/xml/sixtp-utils.c \
   ${top_srcdir}/src/backend/xml/sixtp.c \
   ${top_srcdir}/src/backend/xml/sixtp-stack.c \
@@ -36,8 +36,8 @@ test_kvp_frames_SOURCES = \
 # and remain portable.
 
 test_load_example_account_SOURCES = \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.c \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.c \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.cpp \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.cpp \
   ${top_srcdir}/src/backend/xml/sixtp-utils.c \
   ${top_srcdir}/src/backend/xml/sixtp.c \
   ${top_srcdir}/src/backend/xml/sixtp-stack.c \
@@ -60,8 +60,8 @@ test_load_example_account_SOURCES = \
   test-load-example-account.c
 
 test_string_converters_SOURCES = \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.c \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.c \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.cpp \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.cpp \
   ${top_srcdir}/src/backend/xml/sixtp-utils.c \
   ${top_srcdir}/src/backend/xml/sixtp.c \
   ${top_srcdir}/src/backend/xml/sixtp-stack.c \
@@ -70,8 +70,8 @@ test_string_converters_SOURCES = \
   test-string-converters.c
 
 test_xml_account_SOURCES = \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.c \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.c \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.cpp \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.cpp \
   ${top_srcdir}/src/backend/xml/sixtp-utils.c \
   ${top_srcdir}/src/backend/xml/sixtp.c \
   ${top_srcdir}/src/backend/xml/sixtp-stack.c \
@@ -93,8 +93,8 @@ test_xml_account_SOURCES = \
   test-xml-account.c
 
 test_xml_commodity_SOURCES = \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.c \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.c \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.cpp \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.cpp \
   ${top_srcdir}/src/backend/xml/sixtp-utils.c \
   ${top_srcdir}/src/backend/xml/sixtp.c \
   ${top_srcdir}/src/backend/xml/sixtp-stack.c \
@@ -116,8 +116,8 @@ test_xml_commodity_SOURCES = \
   test-xml-commodity.c
 
 test_xml_pricedb_SOURCES = \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.c \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.c \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.cpp \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.cpp \
   ${top_srcdir}/src/backend/xml/sixtp-utils.c \
   ${top_srcdir}/src/backend/xml/sixtp.c \
   ${top_srcdir}/src/backend/xml/sixtp-stack.c \
@@ -139,8 +139,8 @@ test_xml_pricedb_SOURCES = \
   test-xml-pricedb.c
 
 test_xml_transaction_SOURCES = \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.c \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.c \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.cpp \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.cpp \
   ${top_srcdir}/src/backend/xml/sixtp-utils.c \
   ${top_srcdir}/src/backend/xml/sixtp.c \
   ${top_srcdir}/src/backend/xml/sixtp-stack.c \
@@ -162,8 +162,8 @@ test_xml_transaction_SOURCES = \
   test-xml-transaction.c
 
 test_xml2_is_file_SOURCES = \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.c \
-  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.c \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-parsers.cpp \
+  ${top_srcdir}/src/backend/xml/sixtp-dom-generators.cpp \
   ${top_srcdir}/src/backend/xml/sixtp-utils.c \
   ${top_srcdir}/src/backend/xml/sixtp.c \
   ${top_srcdir}/src/backend/xml/sixtp-stack.c \