diff --git a/tester/liblinphone_tester.h b/tester/liblinphone_tester.h
index 152dd6dd3..de781c469 100644
--- a/tester/liblinphone_tester.h
+++ b/tester/liblinphone_tester.h
@@ -46,6 +46,7 @@ extern "C" {
 #endif
 
 extern const char *liblinphone_tester_file_prefix;
+extern const char *liblinphone_tester_writable_dir_prefix;
 extern test_suite_t setup_test_suite;
 extern test_suite_t register_test_suite;
 extern test_suite_t call_test_suite;
@@ -68,6 +69,7 @@ extern void liblinphone_tester_init(void);
 extern void liblinphone_tester_uninit(void);
 extern int liblinphone_tester_run_tests(const char *suite_name, const char *test_name);
 extern void liblinphone_tester_set_fileprefix(const char* file_prefix);
+extern void liblinphone_tester_set_writable_dir_prefix(const char* writable_dir_prefix);
 
 #ifdef __cplusplus
 };
diff --git a/tester/message_tester.c b/tester/message_tester.c
index 09872e565..37c79bbfe 100644
--- a/tester/message_tester.c
+++ b/tester/message_tester.c
@@ -453,7 +453,7 @@ static void message_storage_migration() {
 	char src_db[256];
 	char tmp_db[256];
 	snprintf(src_db,sizeof(src_db), "%s/messages.db", liblinphone_tester_file_prefix);
-	snprintf(tmp_db,sizeof(tmp_db), "%s/tmp.db", liblinphone_tester_file_prefix);
+	snprintf(tmp_db,sizeof(tmp_db), "%s/tmp.db", liblinphone_tester_writable_dir_prefix);
 
 	CU_ASSERT_EQUAL_FATAL(message_tester_copy_file(src_db, tmp_db), 1);
 
diff --git a/tester/tester.c b/tester/tester.c
index 3e09be635..da8552ab5 100644
--- a/tester/tester.c
+++ b/tester/tester.c
@@ -49,6 +49,9 @@ const char *liblinphone_tester_file_prefix="./app/native/assets/";
 const char *liblinphone_tester_file_prefix=".";
 #endif
 
+/* TODO: have the same "static" for QNX and windows as above? */
+const char *liblinphone_tester_writable_dir_prefix = ".";
+
 const char *userhostsfile = "tester_hosts";
 
 void liblinphone_tester_clock_start(MSTimeSpec *start){
@@ -326,6 +329,10 @@ void liblinphone_tester_set_fileprefix(const char* file_prefix){
 	liblinphone_tester_file_prefix = file_prefix;
 }
 
+void liblinphone_tester_set_writable_dir_prefix(const char* writable_dir_prefix){
+	liblinphone_tester_writable_dir_prefix = writable_dir_prefix;
+}
+
 
 void liblinphone_tester_init(void) {
 	add_test_suite(&setup_test_suite);