diff --git a/config.c b/config.c
index 81db5d8..d1ff2aa 100644
--- a/config.c
+++ b/config.c
@@ -16,7 +16,7 @@
 void
 config_load_default(zathura_t* zathura)
 {
-  if (!zathura || !zathura->ui.session) {
+  if (zathura == NULL || zathura->ui.session == NULL) {
     return;
   }
 
diff --git a/page_view_widget.c b/page_view_widget.c
index c5a76b4..71dc6de 100644
--- a/page_view_widget.c
+++ b/page_view_widget.c
@@ -242,7 +242,7 @@ zathura_page_view_update_surface(ZathuraPageView* widget, cairo_surface_t* surfa
 {
   zathura_page_view_private_t* priv = ZATHURA_PAGE_VIEW_GET_PRIVATE(widget);
   g_static_mutex_lock(&(priv->lock));
-  if (priv->surface) {
+  if (priv->surface != NULL) {
     cairo_surface_destroy(priv->surface);
   }
   priv->surface = surface;