diff --git a/compositor/main.c b/compositor/main.c
index e7247c947..2c15d16aa 100644
--- a/compositor/main.c
+++ b/compositor/main.c
@@ -3283,15 +3283,12 @@ wet_main(int argc, char *argv[], const struct weston_testsuite_data *test_data)
 			backend = weston_choose_default_backend();
 	}
 
-	wet.compositor = weston_compositor_create(display, log_ctx, &wet);
+	wet.compositor = weston_compositor_create(display, log_ctx, &wet, test_data);
 	if (wet.compositor == NULL) {
 		weston_log("fatal: failed to create compositor\n");
 		goto out;
 	}
 
-	if (test_data)
-		weston_compositor_test_data_init(wet.compositor, test_data);
-
 	protocol_scope =
 		weston_log_ctx_add_log_scope(log_ctx, "proto",
 					     "Wayland protocol dump for all clients.\n",
diff --git a/include/libweston/libweston.h b/include/libweston/libweston.h
index 101b2b72d..44c7f24d6 100644
--- a/include/libweston/libweston.h
+++ b/include/libweston/libweston.h
@@ -197,6 +197,14 @@ struct weston_testsuite_quirks {
 };
 
 /** Weston test suite data that is given to compositor
+ *
+ * It contains two members:
+ *
+ * 1. The struct weston_testsuite_quirks, which can be used by the tests to
+ *    change certain behavior of Weston when running these tests.
+ * 2. The void *test_private_data member which can be used by the testsuite of
+ *    projects that uses libweston in order to give arbitrary test data to the
+ *    compositor. Its type should be defined by the testsuite of the project.
  *
  * \sa compositor_setup
  * \ingroup testharness
@@ -1798,11 +1806,9 @@ weston_compositor_destroy(struct weston_compositor *ec);
 
 struct weston_compositor *
 weston_compositor_create(struct wl_display *display,
-			 struct weston_log_context *log_ctx, void *user_data);
+			 struct weston_log_context *log_ctx, void *user_data,
+			 const struct weston_testsuite_data *test_data);
 
-void
-weston_compositor_test_data_init(struct weston_compositor *ec,
-				 const struct weston_testsuite_data *test_data);
 void *
 weston_compositor_get_test_data(struct weston_compositor *ec);
 
diff --git a/libweston/compositor.c b/libweston/compositor.c
index 643425922..1a88f9644 100644
--- a/libweston/compositor.c
+++ b/libweston/compositor.c
@@ -7327,36 +7327,6 @@ debug_scene_graph_cb(struct weston_log_subscription *sub, void *data)
 	weston_log_subscription_complete(sub);
 }
 
-/** Init the compositor testsuite data
- *
- * The struct weston_testsuite_data contains two members:
- *
- *  1. The struct weston_testsuite_quirks, which can be used by the tests to
- *  change certain behavior of Weston when running these tests.
- *
- *  2. The void *test_private_data member which can be used by the test suite
- *  of projects that uses libweston in order to give arbitrary test data to the
- *  compositor. Its type should be defined by the test suite of the project.
- *
- * This function can be called at most once per compositor instance, just after
- * creating the weston_compositor object and never again. This happens because
- * changing the quirks after e.g. loading the backend is not going to work,
- * there are certain behaviors that need to be set up before this point.
- *
- * \param ec The weston compositor.
- * \param test_data The testsuite data.
- *
- * \ingroup compositor
- * \sa weston_compositor_get_test_data
- */
-WL_EXPORT void
-weston_compositor_test_data_init(struct weston_compositor *ec,
-				 const struct weston_testsuite_data *test_data)
-{
-	assert(ec->backend == NULL);
-	ec->test_data = *test_data;
-}
-
 /** Retrieve testsuite data from compositor
  *
  * The testsuite data can be defined by the test suite of projects that uses
@@ -7383,6 +7353,7 @@ weston_compositor_get_test_data(struct weston_compositor *ec)
  * \param display The Wayland display to be used.
  * \param user_data A pointer to an object that can later be retrieved
  * \param log_ctx A pointer to weston_debug_compositor
+ * \param test_data Optional testsuite data, or NULL.
  * using the \ref weston_compositor_get_user_data function.
  * \return The compositor instance on success or NULL on failure.
  *
@@ -7390,8 +7361,8 @@ weston_compositor_get_test_data(struct weston_compositor *ec)
  */
 WL_EXPORT struct weston_compositor *
 weston_compositor_create(struct wl_display *display,
-			 struct weston_log_context *log_ctx,
-			 void *user_data)
+			 struct weston_log_context *log_ctx, void *user_data,
+			 const struct weston_testsuite_data *test_data)
 {
 	struct weston_compositor *ec;
 	struct wl_event_loop *loop;
@@ -7403,6 +7374,9 @@ weston_compositor_create(struct wl_display *display,
 	if (!ec)
 		return NULL;
 
+	if (test_data)
+		ec->test_data = *test_data;
+
 	ec->weston_log_ctx = log_ctx;
 	ec->wl_display = display;
 	ec->user_data = user_data;