diff --git a/src/test/app_test.cc b/src/test/app_test.cc
index 01099313b3..ea4e69963b 100644
--- a/src/test/app_test.cc
+++ b/src/test/app_test.cc
@@ -342,7 +342,7 @@ TEST(User, DeletesZombies) {
     ASSERT_FALSE(te->IsMarkedAsDeletedOnServer());
 
     std::string json =
-        loadTestDataFile("../testdata/me_without_time_entries.json");
+        loadTestDataFile(std::string("../testdata/me_without_time_entries.json"));
 
     ASSERT_EQ(noError,
               user.LoadUserAndRelatedDataFromJSONString(json, true));
@@ -394,7 +394,7 @@ TEST(Database, AllowsSameEmail) {
     ASSERT_EQ(noError, db.instance()->SaveUser(&user, true, &changes));
 
     User user2;
-    std::string json = loadTestDataFile("../testdata/same_email.json");
+    std::string json = loadTestDataFile(std::string("../testdata/same_email.json"));
     ASSERT_EQ(noError,
               user2.LoadUserAndRelatedDataFromJSONString(json, true));
 
@@ -470,7 +470,7 @@ TEST(Database, SavesAndLoadsObmExperiments) {
     ASSERT_EQ(noError,
               user.LoadUserAndRelatedDataFromJSONString(loadTestData(), true));
 
-    std::string json = loadTestDataFile("../testdata/obm_response.json");
+    std::string json = loadTestDataFile(std::string("../testdata/obm_response.json"));
     Json::Value data = jsonStringToValue(json);
     user.LoadObmExperiments(data);
 
@@ -502,7 +502,7 @@ TEST(Database, SavesAndLoadsObmExperimentsArray) {
     ASSERT_EQ(noError,
               user.LoadUserAndRelatedDataFromJSONString(loadTestData(), true));
 
-    std::string json = loadTestDataFile("../testdata/obm_response_array.json");
+    std::string json = loadTestDataFile(std::string("../testdata/obm_response_array.json"));
     Json::Value data = jsonStringToValue(json);
     user.LoadObmExperiments(data);
 
@@ -1300,7 +1300,7 @@ TEST(User, Continue) {
 TEST(TimeEntry, SetDurationOnRunningTimeEntryWithDurOnlySetting) {
     testing::Database db;
 
-    std::string json = loadTestDataFile("../testdata/user_with_duronly.json");
+    std::string json = loadTestDataFile(std::string("../testdata/user_with_duronly.json"));
 
     User user;
     ASSERT_EQ(noError,
diff --git a/src/test/test_data.cc b/src/test/test_data.cc
index 13f4174be1..d50cc8c704 100644
--- a/src/test/test_data.cc
+++ b/src/test/test_data.cc
@@ -16,7 +16,7 @@ std::string loadTestData() {
     return loadFromTestDataDir("me.json");
 }
 
-std::string loadFromTestDataDir(const char* filename) {
+std::string loadFromTestDataDir(const std::string &filename) {
     return loadTestDataFile(std::string(TESTDATADIR) + filename);
 }
 
diff --git a/src/test/test_data.h b/src/test/test_data.h
index 80d0241173..94e762127e 100644
--- a/src/test/test_data.h
+++ b/src/test/test_data.h
@@ -6,7 +6,7 @@
 #include <string>
 
 std::string loadTestData();
-std::string loadFromTestDataDir(const char* filename);
+std::string loadFromTestDataDir(const std::string &filename);
 std::string loadTestDataFile(const std::string &filename);
 
 #endif  // SRC_TEST_TEST_DATA_H_
diff --git a/src/test/toggl_api_test.cc b/src/test/toggl_api_test.cc
index f32e73317b..c09243294e 100644
--- a/src/test/toggl_api_test.cc
+++ b/src/test/toggl_api_test.cc
@@ -1856,7 +1856,7 @@ TEST(toggl_api, toggl_set_time_entry_end) {
 TEST(toggl_api, toggl_set_time_entry_end_prefers_same_day) {
     testing::App app;
     std::string json =
-        loadFromTestDataDir("time_entry_ending_tomorrow.json");
+        loadFromTestDataDir(std::string("time_entry_ending_tomorrow.json"));
     ASSERT_TRUE(testing_set_logged_in_user(app.ctx(), json.c_str()));
 
     toggl::TimeEntry te = testing::testresult::time_entry_by_id(89818605);