diff --git a/main.c b/main.c
index 27bcfe3..04c0bb0 100644
--- a/main.c
+++ b/main.c
@@ -908,7 +908,11 @@ int main(int argc, char **argv) {
 	wl_list_init(&state.surfaces);
 	state.xkb.context = xkb_context_new(XKB_CONTEXT_NO_FLAGS);
 	state.display = wl_display_connect(NULL);
-	assert(state.display);
+	if (!state.display) {
+		sway_abort("Unable to connect to the compositor. "
+				"If your compositor is running, check or set the "
+				"WAYLAND_DISPLAY environment variable.");
+	}
 
 	struct wl_registry *registry = wl_display_get_registry(state.display);
 	wl_registry_add_listener(registry, &registry_listener, &state);