diff --git a/tinywl/tinywl.c b/tinywl/tinywl.c
index 6c043ed51..ead06fcf8 100644
--- a/tinywl/tinywl.c
+++ b/tinywl/tinywl.c
@@ -250,6 +250,7 @@ static void server_new_keyboard(struct tinywl_server *server,
 	struct wlr_keyboard *wlr_keyboard = wlr_keyboard_from_input_device(device);
 
 	struct tinywl_keyboard *keyboard = calloc(1, sizeof(*keyboard));
+	assert(keyboard);
 	keyboard->server = server;
 	keyboard->wlr_keyboard = wlr_keyboard;
 
@@ -625,6 +626,7 @@ static void server_new_output(struct wl_listener *listener, void *data) {
 
 	/* Allocates and configures our state for this output */
 	struct tinywl_output *output = calloc(1, sizeof(*output));
+	assert(output);
 	output->wlr_output = wlr_output;
 	output->server = server;
 
@@ -801,6 +803,7 @@ static void server_new_xdg_toplevel(struct wl_listener *listener, void *data) {
 
 	/* Allocate a tinywl_toplevel for this surface */
 	struct tinywl_toplevel *toplevel = calloc(1, sizeof(*toplevel));
+	assert(toplevel);
 	toplevel->server = server;
 	toplevel->xdg_toplevel = xdg_toplevel;
 	toplevel->scene_tree =
@@ -859,6 +862,7 @@ static void server_new_xdg_popup(struct wl_listener *listener, void *data) {
 	struct wlr_xdg_popup *xdg_popup = data;
 
 	struct tinywl_popup *popup = calloc(1, sizeof(*popup));
+	assert(popup);
 	popup->xdg_popup = xdg_popup;
 
 	/* We must add xdg popups to the scene graph so they get rendered. The