diff --git a/Subsurface-mobile.pro b/Subsurface-mobile.pro
index 80bede346..e8d43bfbf 100644
--- a/Subsurface-mobile.pro
+++ b/Subsurface-mobile.pro
@@ -43,7 +43,7 @@ SOURCES += subsurface-mobile-main.cpp \
 	core/windowtitleupdate.cpp \
 	core/file.c \
 	core/fulltext.cpp \
-	core/subsurfacestartup.c \
+	core/subsurfacestartup.cpp \
 	core/pref.c \
 	core/profile.c \
 	core/device.cpp \
diff --git a/core/CMakeLists.txt b/core/CMakeLists.txt
index f5166a6ae..fbc9c8013 100644
--- a/core/CMakeLists.txt
+++ b/core/CMakeLists.txt
@@ -173,7 +173,7 @@ set(SUBSURFACE_CORE_LIB_SRCS
 	strtod.c
 	subsurface-float.h
 	subsurface-string.h
-	subsurfacestartup.c
+	subsurfacestartup.cpp
 	subsurfacestartup.h
 	subsurfacesysinfo.cpp
 	subsurfacesysinfo.h
diff --git a/core/subsurfacestartup.c b/core/subsurfacestartup.cpp
similarity index 96%
rename from core/subsurfacestartup.c
rename to core/subsurfacestartup.cpp
index 4a97a683f..23e91bd4f 100644
--- a/core/subsurfacestartup.c
+++ b/core/subsurfacestartup.cpp
@@ -25,7 +25,7 @@ char *testqml = NULL;
  */
 bool imported = false;
 
-void print_version()
+extern "C" void print_version()
 {
 	static bool version_printed = false;
 	if (version_printed)
@@ -43,7 +43,7 @@ void print_version()
 	version_printed = true;
 }
 
-void print_files()
+extern "C" void print_files()
 {
 	struct git_info info = { };
 	const char *filename;
@@ -95,7 +95,7 @@ static void print_help()
 	printf("\n --cloud-timeout=<nr>  Set timeout for cloud connection (0 < timeout < 60)\n\n");
 }
 
-void parse_argument(const char *arg)
+extern "C" void parse_argument(const char *arg)
 {
 	const char *p = arg + 1;
 
@@ -169,7 +169,7 @@ void parse_argument(const char *arg)
 			}
 #elif SUBSURFACE_MOBILE_DESKTOP
 			if (strncmp(arg, "--testqml=", sizeof("--testqml=") - 1) == 0) {
-				testqml = malloc(strlen(arg) - sizeof("--testqml=") + 1);
+				testqml = (char *)malloc(strlen(arg) - sizeof("--testqml=") + 1);
 				strcpy(testqml, arg + sizeof("--testqml=") - 1);
 				return;
 			}
@@ -198,7 +198,7 @@ void parse_argument(const char *arg)
  * I guess Burma and Liberia should trigger this too. I'm too
  * lazy to look up the territory names, though.
  */
-void setup_system_prefs(void)
+extern "C" void setup_system_prefs(void)
 {
 	const char *env;