diff --git a/main.c b/main.c
index e432cf7..1ae8b88 100644
--- a/main.c
+++ b/main.c
@@ -46,14 +46,14 @@ struct _shape
 
 void shape_area(void *self)
 {
-    struct _shape *this = (struct _shape *)self;
-    this->vtb->area(self);
+    struct _shape *pthis = (struct _shape *)self;
+    pthis->vtb->area(self);
 }
 
 void shape_draw(void *self)
 {
-    struct _shape *this = (struct _shape *)self;
-    this->vtb->draw(self);
+    struct _shape *pthis = (struct _shape *)self;
+    pthis->vtb->draw(self);
 }
 
 PRIVATE void _shape_area(void *self)