diff --git a/glib/gtestutils.c b/glib/gtestutils.c
index 7a483a9a0..0357ee9eb 100644
--- a/glib/gtestutils.c
+++ b/glib/gtestutils.c
@@ -1647,6 +1647,15 @@ find_suite (gconstpointer l, gconstpointer s)
   return strcmp (suite->name, str);
 }
 
+static gint
+find_case (gconstpointer l, gconstpointer s)
+{
+  const GTestCase *tc = l;
+  const gchar *str = s;
+
+  return strcmp (tc->name, str);
+}
+
 /**
  * GTestFixtureFunc:
  * @fixture: the test fixture
@@ -1712,7 +1721,12 @@ g_test_add_vtable (const char       *testpath,
         }
       else /* islast */
         {
-          GTestCase *tc = g_test_create_case (seg, data_size, test_data, data_setup, fixture_test_func, data_teardown);
+          GTestCase *tc;
+
+          if (g_slist_find_custom (suite->cases, seg, find_case))
+            g_error ("duplicate test case path: %s", testpath);
+
+          tc = g_test_create_case (seg, data_size, test_data, data_setup, fixture_test_func, data_teardown);
           g_test_suite_add (suite, tc);
         }
     }
diff --git a/glib/tests/autoptr.c b/glib/tests/autoptr.c
index df9edd852..676ee0733 100644
--- a/glib/tests/autoptr.c
+++ b/glib/tests/autoptr.c
@@ -438,7 +438,6 @@ main (int argc, gchar *argv[])
   g_test_add_func ("/autoptr/g_tree", test_g_tree);
   g_test_add_func ("/autoptr/g_variant", test_g_variant);
   g_test_add_func ("/autoptr/g_variant_builder", test_g_variant_builder);
-  g_test_add_func ("/autoptr/g_variant_builder", test_g_variant_builder);
   g_test_add_func ("/autoptr/g_variant_iter", test_g_variant_iter);
   g_test_add_func ("/autoptr/g_variant_dict", test_g_variant_dict);
   g_test_add_func ("/autoptr/g_variant_type", test_g_variant_type);
diff --git a/glib/tests/base64.c b/glib/tests/base64.c
index 2d6b3a162..3d3ba60b2 100644
--- a/glib/tests/base64.c
+++ b/glib/tests/base64.c
@@ -394,9 +394,9 @@ main (int argc, char *argv[])
   g_test_add_data_func ("/base64/incremental/nobreak/3", GINT_TO_POINTER (DATA_SIZE - 2), test_incremental_nobreak);
   g_test_add_data_func ("/base64/incremental/break/3", GINT_TO_POINTER (DATA_SIZE - 2), test_incremental_break);
 
-  g_test_add_data_func ("/base64/incremental/nobreak/4", GINT_TO_POINTER (1), test_incremental_nobreak);
-  g_test_add_data_func ("/base64/incremental/nobreak/4", GINT_TO_POINTER (2), test_incremental_nobreak);
-  g_test_add_data_func ("/base64/incremental/nobreak/4", GINT_TO_POINTER (3), test_incremental_nobreak);
+  g_test_add_data_func ("/base64/incremental/nobreak/4-a", GINT_TO_POINTER (1), test_incremental_nobreak);
+  g_test_add_data_func ("/base64/incremental/nobreak/4-b", GINT_TO_POINTER (2), test_incremental_nobreak);
+  g_test_add_data_func ("/base64/incremental/nobreak/4-c", GINT_TO_POINTER (3), test_incremental_nobreak);
 
   g_test_add_func ("/base64/encode", test_base64_encode);
   g_test_add_func ("/base64/decode", test_base64_decode);