How do I make a wall block light in 2D?

I have a 2D Puzzle Platformer that I am working on that has ambient lighting (One of the mechanics revolves around lighting). I am currently having a problem where light will go through walls, like so: 64771-141e835fd5c64190ca7e919de74717fd.png
Is there any way, short of creating a new shader, to prevent this from happening?

EDIT: Just as clarification I am using Sprite Renderers on everything you see and the Sprites/Diffuse Shader.

Search for dynamic lighting and shadows 2d in the asset store, there a few assets for free